CHAPTER 1 Geriatric Physical Therapy in the 21st Century ciples of optimal agin nd Asking an Answerable Question adults if given the opportunity to fully participate in Converting a need for information into a searchable rehabilitation. clinical question is the first step of an evidence-based beli rgy people who firmly Taking a few mome ts to formulate a clear eve in ther n the challe ds t n patient who ne rustration as thousands of sible pie related to the real ques odel clinica ma0。a the that shou are essential n in o atr Th or diagn osis)th int nd (diagnos sis),and the outco e.Some commo recognize the positive cha f mastering the man- compl group of patients are as technical making comp 1.The Patient.This nent should n y the seareh during which the learner starts with uncomplicated stan to an applicable subgro oup of older adults.For exam- esses to complex and ariable ple,a clinician working with two differen ones. varia stenosis.Or typically mastered after the lower levels.Part of thetr and generally healthy senior athlete The best evidence tion from novice to expert is the increasing ease with proach to the frail older adult and complex situation, tly)ana Dest thlete Con e ns.Because the atien includ pa aplex and variable than the typical younger natient such as community-dwelling or nursing home resident (institutional); well-older adult,generally healthy,or apists shoul seek rail older adu 85 85 2.Intervention:This portion of the answerable question NALYZING,AND APPLYING represents the patient management focus of a ques ion(therapy ostic tool prognost evidence into clinical dec factors,che the miting the making is the second maior anchor of evidence-based considerations of the older adult practice.We live in an information age.For almost any 3.Comparison intervention:A question about the ef- fectiveness of a given intervention or diagnostic pro ogy. re is o commonly accepted usual care?"or ()"Does a new credible,clinically important,and applicable to the ve a better outcome than no interven specifc patient sit ation Whe an un miliar clinical situ on,a cli h erventions are typi identify missing evidence needed to guide 4.Outcomes:Carefully considering the specific out- making.A fou step process is typically used to locate and comes of interest is a good way of focusing the nce:(1)asking a search that is most useful in guid searching the able clinical ques re an evidenc ing the nd (4)de e of care improve functional mobility,increase the patient's ability to participate process and provides insights into applying these principles or improve overall in geriatric physical therapy. essing specih
CHAPTER 1 Geriatric Physical Therapy in the 21st Century 7 firm believers in the principles of optimal aging and had a genuine high regard for the capabilities of older adults if given the opportunity to fully participate in rehabilitation. Geriatric experts are high-energy people who firmly believe in their role and responsibility as a patient advocate, and they thrive on the challenge of the complex patient who needs creativity and individualization of approach, good interpersonal skills, and deep knowledge of the specialty content. These specialists model clinical excellence by not settling for less than what the patient is capable of. Physical therapists are essential practitioners in geriatrics. The physical therapist must embrace this essential role—and recognize the positive challenge—of mastering the management of a complex and variable group of patients. Skill acquisition in any specialty area consists of technical, perceptual, and decision-making components during which the learner starts with uncomplicated standard situations and progresses to complex and variable ones. Performing in a highly complex and variable environment requires the highest level of decision making— typically mastered after the lower levels. Part of the transition from novice to expert is the increasing ease with which a person can enter a new and complex situation, quickly (and increasingly implicitly) analyze the various components, and then make effective and efficient decisions. Because the typical older adult patient is more complex and variable than the typical younger patient, the level of expertise required is particularly high. Less experienced physical therapists should seek mentorship and residency opportunities and engage in active and frequent reflection with peers to develop these skills. FINDING, ANALYZING, AND APPLYING BEST EVIDENCE Incorporation of best evidence into clinical decision making is the second major anchor of evidence-based practice. We live in an information age. For almost any topic, an overwhelming amount of information can be accessed in seconds using computer technology. The challenge, as evidence-based practitioners, is to quickly identify and apply best evidence. The best evidence is credible, clinically important, and applicable to the specific patient situation. When faced with an unfamiliar clinical situation, a clinician reflects on past knowledge and experience, and may identify missing evidence needed to guide their decision making. A four-step process is typically used to locate and apply best evidence: (1) asking a searchable clinical question, (2) searching the literature and locating evidence, (3) critically assessing the evidence, and (4) determining the applicability of the evidence to a specific patient situation. The following section describes each step in this process and provides insights into applying these principles in geriatric physical therapy. Asking an Answerable Question Converting a need for information into a searchable clinical question is the first step of an evidence-based approach. Taking a few moments to formulate a clear search question can considerably facilitate the search process. A poorly formulated question often leads to frustration as thousands of possible pieces of evidence may be identified, most of which are only tangentially related to the real question. Strauss et al.2 identify four major components of a clinical question that should guide a search for evidence: the patient, the intervention (or diagnosis/prognosis), the comparison intervention (diagnosis, prognosis), and the outcome. Some common themes when considering an answerable question related to older adults are as follows: 1. The Patient. This component should narrow the search to an applicable subgroup of older adults. For example, a clinician may be working with two different patients, each with a diagnosis of spinal stenosis. One patient is 92 years old and frail; the other is a very fit and generally healthy senior athlete. The best evidence to guide the clinical approach to the frail older adult with spinal stenosis is likely to be different from the best evidence for the senior athlete. Consider a more complete description of the patient beyond spinal stenosis. For example, include modifiers as appropriate such as community-dwelling or nursing home resident (institutional); well-older adult, generally healthy, or frail older adult; independently functioning or dependent; young-old (age 60 to 75 years), old (age 75 to 85 years), old-old (older than age 85 years). 2. Intervention: This portion of the answerable question represents the patient management focus of a question (therapy, diagnosis or diagnostic tool, prognostic factors, etc.). The information delimiting the patient section will help to focus the evidence on the unique considerations of the older adult. 3. Comparison intervention: A question about the effectiveness of a given intervention or diagnostic procedure is often asking one of two questions: (a) “Does a new intervention have better outcomes than the commonly accepted usual care?” or (b) “Does a new intervention have a better outcome than no intervention at all?” Either question may be important given the likelihood that alternative interventions are typically available and recommended. 4. Outcomes: Carefully considering the specific outcomes of interest is a good way of focusing the search for the evidence that is most useful in guiding the specific episode of care. For example, does the primary question relate to the best approach to remediate a key impairment, improve functional mobility, increase the patient’s ability to participate in activities, or improve overall quality of life? Typically, there are more studies addressing specific
8 CHAPTER 1 Geriatric Physical Therapy in the 21st Century eviden e phy apy manag ment suppo atic re Searching the Literature and stron mendations.More commonly,best evidence consists of the integration of the finding of one or several individ nto secondar al studies varying quality s wh The d sed p able dgm and analyses of these primary studies.The ideal evidence locate,categorize,int rpret,and svnthesize the available that is readily available evidence and also judge its relevance to the particular easily acces rmatte st bons hncratey Phys 1-5 and Bos an organi portance,and applicability of primary research arti mid with foundational studies at the bottom of the cles as well as being able to choose appropriate second ary sources Geriatric physic top of th is from truste rapof kr area requ ule high-aualiry ythe rly)clin ndies (the firs a wide variety of evidence sourc Foundationalstudiesprovideehcof As depicted in Box 1-1,each piece of evidence falls heor to the rom foundation ramewrkand obervations thatpr ons c o with gn-qu direct and vide direction to future research and sug where a specific type of evidence falls within the con and a clo r review is o answers to search to answer lguecsti9ehnitiveiniaec tion (i. mos certainty about the ications of the findings)is patients under typically derived from the recommendations emerging hehad typical conditions and provide sufficiently long follow rev e most valuable in ou 1-qu2 directly are the search for best primary ence.These stuc les,terme es.are BOX 1-1 Continuum of Evide nce studies Rep senting Early Foundational Concepts Through Integration of Findings Across Multiple Studies Aggr epts Evidence riptivestudies wi油hig Syst dea rs (based on theorie ility validity: Evider 59 afaty and notential for .D and ll Clinical trialsphase ll and IV ed c xper se l et narketing studies delineate additional information incuding the documented risks,benefits,and optimal use
8 CHAPTER 1 Geriatric Physical Therapy in the 21st Century impairments and functional activity than participation and quality of life. Searching the Literature Sources of Evidence. The scientific literature is divided into two broad categories: primary and secondary sources. The primary sources are the original reports of research studies. Secondary sources represent reviews and analyses of these primary studies. The ideal evidence source is a trusted resource that is readily available, easily accessed, and formatted to answer your specific questions quickly and accurately. Physical therapists must be competent in finding and assessing the quality, importance, and applicability of primary research articles as well as being able to choose appropriate secondary evidence from trusted sources. Geriatric physical therapy is a broad specialty area requiring an expansive range of knowledge and clinical expertise and, therefore, a wide variety of evidence sources. As depicted in Box 1-1, each piece of evidence falls along a continuum from foundational concepts and theories to the aggregation of high-quality and clinically applicable empirical studies. On casual review of published studies, it is sometimes difficult to determine just where a specific type of evidence falls within the continuum of evidence and a closer review is often required. The highest quality research to answer a clinical question (i.e., providing the strongest evidence that offers the most certainty about the implications of the findings) is typically derived from the recommendations emerging from a valid systematic review that aggregates numerous high-quality studies directly focusing on the clinical question. However, only a very small proportion of evidence associated with the physical therapy management of older adults is well enough developed to support systematic reviews yielding definitive and strong recommendations. More commonly, best evidence consists of the integration of the findings of one or several individual studies of varying quality by practitioners who incorporate this evidence into their clinical judgments. The evidence-based practitioner must be able to quickly locate, categorize, interpret, and synthesize the available evidence and also judge its relevance to the particular situation. Figure 1-5 and Box 1-1 provide an organizational schematic depicting the scientific literature as a pyramid with foundational studies at the bottom of the pyramid and the systematic integration and synthesis of multiple high-quality studies at the top of the pyramid. The literature is replete with both foundational and initial (early) clinical studies (the first two levels of the pyramid). Foundational studies provide theories, frameworks, and observations that spur empirical investigations of topics with clinical applicability but, in and of themselves, have little direct and generalizable clinical applicability. Similarly, early empirical studies provide direction to future research and suggest potential impact but, by themselves, do not provide definitive answers to clinical questions. Studies with a more definitive influence on clinical decisions are higher up on the pyramid. High-quality primary studies that examine typical patients under typical conditions and provide sufficiently long followup are the most valuable in our search for best primary evidence. These studies, termed effectiveness studies, are BOX 1-1 Continuum of Evidence: Studies Representing Early Foundational Concepts Through Integration of Findings Across Multiple Studies *Clinical trials: Foundational Concepts and Theories Initial Testing of Foundational Concepts Definitive Testing of Clinical Applicability Aggregation of the Clinically Applicable Evidence Descriptive studies Case reports Idea papers (based on theories and observations) “Bench research” (cellular or animal model research for initial testing of theories) Opinions of experts in the field (based on experience and review of literature) Single-case design studies Testing on “normals” (no real clinical applicability) Small cohort studies (assessing safety and potential for benefit with real patients) Clinical trials,* phase I and II Well-controlled studies with high internal validity and clearly identified external validity: • Diagnosis • Prognosis • Intervention • Outcomes • Clinical trials,* phase III and IV Systematic review and meta-analysis Evidence-based clinical practice guideline Phase I: examines a small group of people to evaluate treatment safety, determine safe dosage range, and identify side effects. Phase II: examines somewhat larger group of people to evaluate treatment efficacy and safety. Phase III: examines a large group of people to confirm treatment effectiveness, monitor side effects, compare it to commonly used treatments, and further examine safety. Phase IV: postmarketing studies delineate additional information including the documented risks, benefits, and optimal use
CHAPTER 1 Geriatric Physical Therapy in the 21st Century 9 narrowly,to individuals aged 80 years and above hest leve d (rand 0 eeaepead make the search faster and more focused. Cumulative Index of Nursing and Allied Health se that focuses specif er pa foundational concep bership in a libr sional org subscribes to it.The CINAHL database is available fre Founda nal concepts and theories Physical Therap criteri o overlap with many journals indexed evidence from lo in both databases,those indexed in CINAHL but not PubMed tend t be smaller journals containing stu mor locate with few and far bet likely to be The ower on the pyrami t.The c for CINAHLo erformed less werful than PubMed. using unbiased and transparent methodol that Lin the an's spec EVaguestioi vides an utomatic ava pically a tw s:(1)finding nals(at least the volumes p Finding the Citations.The biomedical literature is inde canoed xed according to their citations (tit include t of jour on a ith the tion as well as information about how to access the full provide a link to PubMed directly from their websites. text of the article and whether access is free or requires Accessing PubMed through one of the linked librar ment PubMec sites allows an im ediate link to the full text of any ase t oduct of the Un are av y pa States National Library of Medicine (NLM)at the through Open Door as a member benefit National Institutes of Health (NIH).This database Staying Updated with Evidence.Practitioners(across ansive list of all hea care helds)are ofen unaware of new evd but to th r practic ,o 8n indexed in PubMed must meet high-quality standards. approach.Although both consumers and payers ex practice based on valid evidence,the Institute of Medi cine reports long e can ne free of ag times between publication of t new e ence an link to the publisher who controls access to the article if care practitioners should have a strategy to there is a publisher-controlled charge for access.PubMed regularly review current evidence in their specialty area utilizes a powerfu A simple review of the table of contents of core journals a sea h as n ne topic area ca the user maximize their efficiency and effectiveness usin In addition.choose one or two core iournals in a pro this database.The Medical Subject Heading terminology fessionally applicable subspecialty area (stroke,arthritis. (MeSH)used by PubMed also automatically searche s I teoporosis process to request words that are known synonyms(e.g.,a search of bigh the monthly table of contents of these joumnc
CHAPTER 1 Geriatric Physical Therapy in the 21st Century 9 few and far between in geriatric physical therapy. The highest category of evidence (top of the pyramid) is a systematic review of the existing literature performed using unbiased and transparent methodology that directly addresses the clinician’s specific question. Searching the Literature for Best Evidence. Locating evidence is typically a two-step process: (1) finding the citation and (2) locating the full text of the reference. Finding the Citations. The biomedical literature is cataloged and indexed according to their citations (title, authors, and identifying information about the source). An abstract of the article is often provided with the citation as well as information about how to access the full text of the article and whether access is free or requires membership or payment of a fee. PubMed (pubmed. com) is generally the best database to use to search for biomedical evidence. PubMed is a product of the United States National Library of Medicine (NLM) at the National Institutes of Health (NIH). This database provides citations and abstracts from an expansive list of biomedical journals, most in English, but also including major non-English biomedical journals. All journals indexed in PubMed must meet high-quality standards, thus providing a certain level of comfort about using PubMed-indexed journals as trusted sources. The PubMed database can be searched online free of charge. PubMed provides a link to the full text or to a link to the publisher who controls access to the article if there is a publisher-controlled charge for access. PubMed utilizes a powerful search engine organized to easily narrow or expand a search as needed for efficiency. PubMed provides many free online tutorials that help the user maximize their efficiency and effectiveness using this database. The Medical Subject Heading terminology (MeSH) used by PubMed also automatically searches for words that are known synonyms (e.g., a search of high blood pressure also retrieves articles on hypertension). In the “advance search” mode, you can limit your search to studies focused on older adults (651) or, even more narrowly, to individuals aged 80 years and above. Or you can limit the search to studies in the highest level of the pyramid (randomized controlled trials, phase 3 or 4 clinical trials, systematic reviews). All these features make the search faster and more focused. Cumulative Index of Nursing and Allied Health Literature (CINAHL) is a database that focuses specifically on nursing and allied health. You must either pay to subscribe to CINAHL or gain access through membership in a library or a professional organization that subscribes to it. The CINAHL database is available free of charge to members of the American Physical Therapy Association (APTA). The criteria for being indexed in CINAHL are less stringent than PubMed. Thus, although there is an overlap with many journals indexed in both databases, those indexed in CINAHL but not PubMed tend to be smaller journals containing studies more likely to be located lower on the pyramid with a greater need to be assessed for design flaws that make findings suspect. The search engine for CINAHL is also less powerful than PubMed. Finding Full Text. Accessing through PubMed provides an automatic link to the full text if it is available free of charge. In this electronic era, most biomedical journals (at least the volumes published over the past decade or so) are accessed electronically either from the publisher or from companies that purchase the rights to include the journal’s holdings in a bundled set of journals made available to libraries and other entities for an annual fee. Frequently, university and medical libraries provide a link to PubMed directly from their websites. Accessing PubMed through one of the linked library websites allows an immediate link to the full text of any articles that are available to library patrons. Members of the APTA may similarly access a broad array of journals through Open Door as a member benefit. Staying Updated with Evidence. Practitioners (across all health care fields) are often unaware of new evidence applicable to their practice, or ignore new evidence because it is inconsistent with their accustomed approach. Although both consumers and payers expect practice based on valid evidence, the Institute of Medicine reports long lag times between publication of important new evidence and the incorporation of evidence into practice.14 All health care practitioners should have a strategy to regularly review current evidence in their specialty area. A simple review of the table of contents of core journals in the topic area can be useful. Core journals in geriatrics and geriatric physical therapy are listed in Box 1-2. In addition, choose one or two core journals in a professionally applicable subspecialty area (stroke, arthritis, osteoporosis, etc.). It is a simple process to request the monthly table of contents of these journals; scan the Aggregation of clinically applicable studies Definitive testing of clinical applicability Initial testing of foundational concepts Foundational concepts and theories FIGURE 1-5 Pyramid depicting the organization of scientific evidence from low to high clinical applicability
10 CHAPTER1 Geriatric Physical Therapy in the 21st Century B0X1-2 Relevant a clinica Joumal of the American Geriatric Society ent or situ to your Medical and Biological Sciences Credibility.Searching for credible evidence starts ouus Physical Therapy inthe procyprovide the highest level ofv dence. alidit of the table of contents and carefully select a small number potential studies.Regardless of its general category (i.e. tematic review),the dence,th study wer ngs and reporte of th A second approach is to go to a site such as AMEDEO com).This is a free service providing textbooks A brief summary of selected points is aggrega alons specific provided below care special- studies compare the ld man specialty area (or a subset of these journals as requested) should confirm represent iveness of the subjects in the free PubMed account tha ows a str run periodically to identify any new citations,and have findings of the other to avoid any biasing influence,all the new citations automatically forwarded via e-mail. subjects should undergo the gold standard,and,ideally. cif bMed approach all the the study shoul repeated with a new set of subjects 0 onhrm the with Sources that Translate Evidence into Practice of the outcome of interest.Prognosis studies may follow either one or two groups atients (cohort or case and erature im sources for translatine evidence into of prognosis studies inform particularly on a systemat rev v of the literatu length of tim expert cons re validity dpaicemateicieto the gth of follow-uD. and pro spective desi HealthCare Rese assembled at a common point in the Department of Hea rvice provides a of the di 5 are subjects reason theng me data en e cht at this poin easc,an out larg which the guideline is based.Strength of the evidence nced the predicted outcome?Wer re the outcomes criteria should be based on quality,consist ncy,and number of ree studies supporting the recommendation biases and responsive Critically Assessing the Evidence characteristics or condition of interest in the study.Kev "Best available evidence nce of a a somparison roup to whish ubest of a control ilarity at baseline and low attritiot (collected,analyzed,and reported using unbiased and the study.The methods used in the study should mini- valid processes),is clinically important (the study's mize risk of researcher bias or confounding variables
10 CHAPTER 1 Geriatric Physical Therapy in the 21st Century table of contents and carefully select a small number of particularly applicable articles to read full-text. The higher the article is on the pyramid of evidence, the more likely its findings can be readily applied to clinical practice. A second approach is to go to a site such as AMEDEO (www.amedeo.com). This is a free service providing weekly e-mails aggregating article citations specific to any interest across a wide range of health care specialties. The citations are typically taken from ongoing searches of newly published issues of core journals in the specialty area (or a subset of these journals as requested). A third option is to set up a free PubMed account that allows an individual to identify and save a specific search strategy within PubMed, have the search automatically run periodically to identify any new citations, and have the new citations automatically forwarded via e-mail. The PubMed approach allows you to be the most specific about the characteristics of the studies of interest and searches across the widest variety of journals. Sources that Translate Evidence into Practice Recommendations. Systematic reviews that provide evidence of objective and unbiased synthesis of the full body of literature on a topic, providing unambiguous and well-grounded recommendations, are important sources for translating evidence into practice recommendations. Clinical practice guidelines, particularly those based on a systematic review of the literature and expert consensus in applying the evidence to clinical practice, can be efficient sources of evidence. The National Guideline Clearinghouse of the Agency for HealthCare Research and Quality (AHRQ) of the U.S. Department of Health and Human Services provides a central and searchable guideline database. When examining the Practice Guidelines, confirm the comprehensiveness and objective analysis of the literature on which the guideline is based. Strength of the evidence should be based on quality, consistency, and number of studies supporting the recommendation. Critically Assessing the Evidence “Best available evidence” has become a catch phrase to describe preferred information sources for evidenceinformed practice. But what exactly does best evidence really mean? Best evidence is evidence that is credible (collected, analyzed, and reported using unbiased and valid processes), is clinically important (the study’s findings demonstrate a large enough change to have a clinically meaningful impact), and the credible and important findings are directly applicable to your patient or situation. Credibility. Searching for credible evidence starts out using the procedures described in the previous section to locate studies likely to provide the highest level of evidence. Credibility (quality) is assessed through a critical assessment of the internal and external validity of the potential studies. Regardless of its general category (i.e., therapy, prognosis, diagnosis, or systematic review), the study should provide convincing evidence that data were collected, analyzed, and reported in an unbiased fashion. A full review of the concepts of critical assessment of the biomedical literature is available in several well-organized textbooks.2,15,16 A brief summary of selected points is provided below. Diagnosis studies compare the performance of a new diagnostic test against the current gold standard or its equivalent,17 typically testing the test. Diagnosis studies should confirm representativeness of the subjects in the study and present a solid argument that justifies the choice of gold standard.18 Assessors for reference and target tests should be independent and blinded to the findings of the other to avoid any biasing influence, all subjects should undergo the gold standard, and, ideally, the study should be repeated with a new set of subjects to confirm the findings. Prognosis studies follow subjects with a target disorder or risk factor over time and monitor the occurrence of the outcome of interest. Prognosis studies may follow either one or two groups of patients (cohort or case– control, respectively), preferably prospectively, to examine the impact of various factors on the target disorder. The findings of prognosis studies inform judgments about such things as who is most likely to benefit from rehabilitation or the length of time to achieve rehabilitation goals. Key indicators of credibility and validity of prognosis studies19 include the representativeness of the subjects, length of follow-up, and prospective design. Were subjects assembled at a common point in the course of the disease, are subjects reasonably representative of the typical patient at this point in the disease, and are subjects followed for a sufficiently long time period, without large attrition, to capture everyone who experienced the predicted outcome? Were the outcomes criteria free of patient or practitioner biases and responsive enough to capture the outcome if it occurred? Therapy studies assess the impact of specific interventions on subjects chosen because they possess the specific characteristics or condition of interest in the study. Key indicators of quality in a therapy study are the presence of a control or a comparison group to which subjects were randomly assigned, reasonable between-group similarity at baseline, and low attrition over the course of the study. The methods used in the study should minimize risk of researcher bias or confounding variables BOX 1-2 Key Journals Particularly Relevant to Geriatric Physical Therapy Journal of the American Geriatric Society Journal of Gerontology: Series A; Medical and Biological Sciences Journal of Geriatric Physical Therapy Physical Therapy
CHAPTER 1 Geriatric Physical Therapy in the 21st Century 11 providing plausible alternative explanations for the ob defined)an odds ratio greater than 3 is d a There are several distinguishing features of quality in up:an odds ratio greater than 10 as a verv a systematic review.A systematic review should confirm large increase.Odds ratios less than 1(identified as that a comprehen ve search of the appropriate literature negative odd ratios)that the prs the been pe repro included studies mee t established inclusion criteria.At negative odds ios is 1 to 0.An odds ratio of 0.7 is least two reviewers should independently assess quality generally described as representing a moderate decrease med ).2 as a ver arge fde in od and odds rati ng ih th rified.The ndations nd stat of the ted as the ide strength of the evidence are well grounded and clearly In order for an odds ratio to be considered statisticall nchddonithegais,imdngandappeb (and thus generalizable the scores withi rtance of the Findings as as core 11。 of the study detailed discussion of statistical Diagnosis Studies.Sensitivity,specificity,and likeli. studies is found elsewhere 20 comn nonly reporte hndings of In comparison to logistic regression, aim est 1n6 out ome ong a tha is high a ent location within one of tw likely to rule out the condition,whereas,when specificit ontinuum of s cores based on scores tion 6 bile best f o6eaCrosamcea on pre Fo age or negative test effect with ha onditi edict the gait d of co delling older adults.The outcom of linear r hood ratio (LR+)( rbitrarily identified as a score above would be an equation that can be used to predict the 10)in svery likely to be specific gait or omparabl given the rily id of by the del indicate the des a score below 0.2)indicates that it is very unlikely that to which all the variables included in the model acc the person with a negative test has the condition. Prognosis Studies Progno studie examine the scor cted ely,the ex al tical analysis of choice is a regression analysis.Logistic provides useful information about trends in the popula- regression is utilized more commonly than linear regres- sion because many of the one specific patient. ce or st may ell great in smal f variables.The aim of progn c studies using istic significant predictions that regression is account for as little as 40%of the variance may have some a set pred ments alue in guiding ju rela for 0 of the variance would be perceived as very compelling the end of rehabilitation (as compared to those who go hndings. ns T he mo variability in the predic tor va abl ly the ase in of old ad he is is thu ables are examined and.in combination. ovide a sta. tistically more robust assessment of the odds of obtain- dence in the accuracy of the prediction.Studies may need particularly large sample sizes combin with a large number of w osen predictor variables to explair
CHAPTER 1 Geriatric Physical Therapy in the 21st Century 11 providing plausible alternative explanations for the observed outcomes. There are several distinguishing features of quality in a systematic review. A systematic review should confirm that a comprehensive search of the appropriate literature has been performed using a transparent and reproducible process for identifying studies and confirming that included studies meet established inclusion criteria. At least two reviewers should independently assess quality and applicability of each study considered for the review. Meta-analysis across studies is performed if sufficient numbers of studies with sufficient homogeneity are identified. The recommendations and statement of the strength of the evidence are well grounded and clearly justified based on the quality, findings, and applicability of the included studies. Determining the Importance of the Findings of the Study Diagnosis Studies. Sensitivity, specificity, and likelihood ratios are the most commonly reported findings of studies aimed at establishing the accuracy of diagnostic tools. Several references provide excellent reviews of this topic.2,17 When sensitivity is high, a negative test result is likely to rule out the condition, whereas, when specificity is high, a positive test result is likely to rule in the condition. Likelihood ratios (LRs) are best for increasing the therapist’s confidence in the ability to associate a positive or negative test effect with having the target condition/ disorder (posttest probability).20 A high positive likelihood ratio (LR1) (arbitrarily identified as a score above 7 or 10) indicates that the condition is very likely to be present in the person with a positive test. Conversely, a very low likelihood ratio (LR2) (arbitrarily identified as a score below 0.2) indicates that it is very unlikely that the person with a negative test has the condition. Prognosis Studies. Prognosis studies examine the ability of selected factors to predict an outcome of interest. Most commonly, although not exclusively, the statistical analysis of choice is a regression analysis. Logistic regression is utilized more commonly than linear regression because many of the key explanatory variables (e.g., “sex” or “presence or absence of surgical history”) as well as the outcome of interest are categorical variables. The aim of prognostic studies using logistic regression is to determine the extent to which the presence or absence of selected variables predicts a patient’s outcome or risk of belonging to a target group. For example, how accurately does a set of prognostic variables predict which subjects are likely to go home at the end of rehabilitation (as compared to those who go to a nursing home or other setting)? These predictions provide an estimate of the “odds” of belonging in the target outcome group. Typically, several predictor variables are examined and, in combination, provide a statistically more robust assessment of the odds of obtaining an outcome (i.e., belong to the target group) than one variable alone. By convention (and fairly arbitrarily defined) an odds ratio greater than 3 is generally interpreted as a moderate increase in odds of being in the target group; an odds ratio greater than 10 as a very large increase. Odds ratios less than 1 (identified as negative odds ratios) indicate that the presence of the predictor variables is related to decreased odds of being in the target group. The full range of possible scores for negative odds ratios is 1 to 0. An odds ratio of 0.7 is generally described as representing a moderate decrease in odds of being in the target group, and an odds ratio of 0.2 as a very large decrease in odds of being in the target group. The confidence interval (CI), most commonly reported as the 95% CI, must also be considered. In order for an odds ratio to be considered statistically significant (and thus generalizable), the scores within the bracketed CI must NOT include 1, as a score of 1 represents equal odds of being in either group. A more detailed discussion of statistical analysis and prognosis studies is found elsewhere.20 In comparison to logistic regression, linear regression examines outcomes along a continuum. Rather than focusing on whether or not a set of variables can predict patient location within one of two identified groups, a linear regression analysis wants to determine a specific score across a linear continuum of scores based on scores on predictor variables. For example, patient age, heart rate, and number of chronic health conditions might be hypothesized to predict the gait speed of communitydwelling older adults. The outcome of linear regression would be an equation that can be used to predict the specific gait speed of comparable patients given their scores on each of the predictor variables. The proportion of variance explained by the model indicates the degree to which all the variables included in the model account for the outcome or dependent variable. A model that predicts the outcome score perfectly would be described as explaining all the variance; however, realistically, there is always unexplained variance. Linear regression provides useful information about trends in the population but is often not very useful in predicting the scores of one specific patient. Variability among and between subjects may be too great in small, convenience samples, which is typically the case in the rehabilitation literature. Generally, statistically significant predictions that account for as little as 40% of the variance may have some value in guiding judgments about the relative contributions of a set of predictor variables, and a study that constructed a predictive model accounting for 70% of the variance would be perceived as very compelling findings. The more variability in the predictor variables—as is commonly the case in studies of older adults—the less robust the prediction, thus lowering the odds ratio or percentage of variance explained, which decreases confidence in the accuracy of the prediction. Studies may need particularly large sample sizes combined with a large number of well-chosen predictor variables to explain