The cost of outpatient versus inpatient total hip arthroplasty: a randomized trial.

BACKGROUND: One route to mitigate the increasing costs of total hip arthroplasty (THA) is outpatient THA, discharging patients on the same day as their surgery. The purpose of this study was to compare the cost of outpatient THA to standard overnight stay in hospital. METHODS: This was a preliminary analysis of the first group of patients to complete follow-up in a larger randomized controlled trial among patients who underwent primary THA through a direct anterior approach between June 2015 and November 2017. The study was conducted at a single centre among patients of 1 fellowship-trained arthroplasty surgeon. We randomly allocated participants to be discharged either as outpatients or on postsurgery day 1 using a modified Zelen consent model. Adverse events were recorded. Participants completed cost questionnaires 2, 6 and 12 weeks after surgery, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) before and 12 weeks after surgery. We performed cost analyses from health care payer and societal perspectives. RESULTS: A total of 115 participants completed this study, 49 allocated to the outpatient group and 56 to the inpatient group. The adverse event rate was similar for the 2 groups. The WOMAC total score and function subscale score were higher for the outpatient group than the inpatient group at 12 weeks (mean difference 2.1, 95% confidence interval [CI] 0.0 to 4.1, and 6.5, 95% CI 0.4 to 12.5, respectively). From both a health care payer and a societal perspective, inpatient THA was more costly than outpatient THA (mean difference $1006.86, 95% CI -$2158.92 to $145.21, and $1667.40, 95% CI -$3856.64 to $521.84, respectively). CONCLUSION: Our results suggest that outpatient THA may be a cost-saving procedure compared to inpatient THA from both health care payer and societal perspectives. Further study with larger samples is needed to provide more precision around our estimates. TRIAL REGISTRATION: ClinicalTrials.gov, no. NCT03026764.

Wait times, resource use and health-related quality of life across the continuum of care for patients referred for total knee replacement surgery.

Background: The escalating socioeconomic burden of knee osteoarthritis (OA) underscores the need for innovative strategies to reduce wait times for total knee arthroplasty (TKA). The purpose of this study was to evaluate resource use, costs and health-related quality of life (HRQoL) across the continuum of care for patients with knee OA. Methods: This was a prospective study of 383 patients recruited from a high-volume teaching hospital at different stages of care (referral, consultation and presurgery). Outcomes included health care resource use; costs captured from the health care payer, private sector and societal perspectives; HRQoL measured using the Western Ontario and McMaster Universities Osteoarthritis Index, the 12-Item Short Form Health Survey, and EuroQoL 5-Dimension 5-Level tool; wait times; and the proportion of referrals deemed suitable candidates for surgery. Results: The most commonly used conservative treatments were pharmacotherapy, exercise and lifestyle modification. Forty percent of patients referred for TKA were deemed not to be suitable candidates for surgery. The greatest proportion of costs was borne by the patient or private insurer; a small proportion was borne by the public payer. Across all stages of care, more than 60% of the total costs was attributed to productivity losses. HRQoL remained relatively stable throughout the waiting period (mean wait time from referral to TKA 13.2 mo) but improved postoperatively. Conclusion: The suboptimal primary care management of knee OA calls for the development of innovative models of care. This study may provide valuable guidance on the design and implementation of a new online educational platform to improve referral efficiency and expedite wait times for TKA.

Contexte: Le fardeau socioéconomique croissant de l'arthrose du genou rappelle que nous avons besoin de stratégies novatrices afin de réduire les temps d'attente pour l'arthroplastie totale du genou (ATG). Le but de cette étude est d'évaluer l'utilisation des ressources, les coûts et la qualité de vie liée à la santé (QVLS) dans tout le continuum des soins pour les patients souffrant d'arthrose du genou. Méthodes: Cette étude prospective a porté sur 383 patients recrutés dans un établissement d'enseignement fort achalandé, qui en étaient à différentes étapes du continuum de soins (demande de consultation, consultation et préchirurgie). Les paramètres incluaient l'utilisation des ressources en santé, les coûts du point de vue sociétal et des régimes d'assurance maladie publics et privés, la QVLS mesurée au moyen de l'indice WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), du questionnaire Short Form Health Survey en 12 points et de l'outil EuroQoL appliqué à 5 dimensions et à 5 niveaux, les temps d'attente, et la proportion de demandes de consultation concernant des patients considérés comme de bons candidats à la chirurgie. Résultats: Les traitements conservateurs les plus utilisés étaient la pharmacothérapie, l'exercice et les modifications à l'hygiène de vie. Quarante pour cent des patients adressés en consultation pour ATG ont été considérés comme de bons candidats à la chirurgie. La plus grande part des coûts a été assumée par le patient ou un assureur privé; une faible part des coûts a été assumée par le régime public. À toutes les étapes du continuum, plus de 60 % des coûts totaux ont été attribués à des pertes de productivité. La QVLS est demeurée relativement stable tout au long de la période d'attente (temps d'attente moyen entre la consultation et l'ATG, 13,2 mois) mais s'est améliorée après la chirurgie. Conclusion: La prise en charge sous-optimale de l'arthrose du genou en soins primaires rappelle qu'il est nécessaire d'établir des modèles de soins novateurs. Cette étude pourrait faciliter la mise au point et l'application d'une nouvelle plateforme éducative en ligne pour améliorer l'efficience des demandes de consultation et abréger les temps d'attente pour l'ATG.

Assessment of Informal Caregiver Assistance and Strain With Total Hip and Knee Arthroplasty.

BACKGROUND: The purpose of our study is to assess which patient-related and caregiver-related factors are predictive of caregiver strain and assistance when caring for total hip and knee arthroplasty (THA and TKA) patients within 2 weeks after surgery. METHODS: We conducted a prospective study of caregivers of participants enrolled in 2 randomized trials. Caregivers provided demographics and completed the Caregiver Strain Index and Caregiver Assistance Scale pre-surgery and post-surgery. We performed backwards stepwise regression with mixed-effects negative binomial models to investigate predictors of caregiver strain and assistance for THA and TKA caregivers. RESULTS: Three hundred six caregiver/patient pairs were included. Our models of caregiver strain found Caregiver Assistance Scale scores and patient age to be predictive for all caregivers. We also found caregiver gender and smoking status to be predictive for THA caregivers and caregiver age to be predictive for TKA caregivers. Our models of assistance provided by caregivers found time (post-surgery vs pre-surgery) was predictive for all caregivers. We also found patient body mass index, and patient and caregiver gender to be predictive for THA caregivers, and patient and caregiver employment status and caregiver education level to be predictive for TKA caregivers. CONCLUSION: Our study identifies patient-related and caregiver-related factors which are associated with caregiver strain and assistance when caring for arthroplasty patients. As this is the first study to assess assistance provided by caregivers, it is important for future research to validate our results and to further explore whether patient-reported outcomes may also be related to assistance and strain.

A protocol for a randomized controlled trial investigating the safety and cost-effectiveness of outpatient total hip arthroplasty.

BACKGROUND: A significant proportion of the overall cost of total hip arthroplasty (THA) results from the inpatient hospital stay following the procedure. Considering the substantial and increasing number of these procedures performed annually, shifting to an outpatient model of care where the patient is discharged home the same day as their surgery represents a potential for significant cost savings. The potential significant impact of an outpatient care model on constrained healthcare budgets and lack of high-quality evidence regarding its effectiveness warrants a rigorous comparative trial. The purpose of this prospective, randomized controlled trial is to evaluate outpatient care pathways for THA. Specifically, our objectives are to compare the rate of serious adverse events and estimate the cost-effectiveness of outpatient compared to standard inpatient THA. METHODS: We will include patients undergoing primary THA whom have an American Society of Anaesthetists status equal to or less than three, live within a 60-min driving distance of the institution and have an adult to accompany them home postoperatively and stay with them overnight. Consenting patients will be randomized to be discharged on the same day as surgery, as outpatients, or as inpatients according to standard of care (minimum of one night in hospital) using a modified Zelen consent model. The primary outcome measure is the incidence of serious adverse events at 30 days postoperative. Participants and their caregivers will complete secondary outcomes measures at each follow-up visit including patient-reported outcome measures and self-reported cost questionnaires. DISCUSSION: This protocol is the first randomized trial to use blinding to evaluate outpatient THA compared to standard overnight stay and first to prospectively perform a full economic evaluation. It is also the first adequately powered trial to prospectively assess the safety of outpatient THA. Successful completion of this study could have the potential to provide clinical evidence for the role of outpatient THA in current practice. TRIAL REGISTRATION: This study was retrospectively registered on ClinicalTrials.gov ( NCT03026764 ) on March 9th, 2016.

Clinical Assessment of Physical Examination Maneuvers for Superior Labral Anterior to Posterior Lesions.

Purpose Shoulder pain and disability pose a diagnostic challenge owing to the numerous etiologies and the potential for multiple disorders to exist simultaneously. The evidence to support the use of clinical tests for superior labral anterior to posterior complex (SLAP) is weak or absent. The purpose of this study is to determine the diagnostic validity of physical examination maneuvers for SLAP lesions by performing a methodologically rigorous, clinically applicable study. Methods We recruited consecutive new shoulder patients reporting pain and/or disability. The physician took a history and indicated their certainty about each possible diagnosis ("certain the diagnosis is absent/present," or "uncertain requires further testing"). The clinician performed the physical tests for diagnoses where uncertainty remained. Magnetic resonance imaging arthrogram and arthroscopic examination were the gold standards. We calculated sensitivity, specificity, and likelihood ratios (LRs) and investigated whether combinations of the top tests provided stronger predictions. Results Ninety-three patients underwent physical examination for SLAP lesions. When using the presence of a SLAP lesion (Types I-V) as disease positive, none of the tests was sensitive (10.3-33.3) although they were moderately specific (61.3-92.6). When disease positive was defined as repaired SLAP lesion (including biceps tenodesis or tenotomy), the sensitivity (10.5-38.7) and specificity (70.6-93.8) of tests improved although not by a substantial amount. None of the tests was found to be clinically useful for predicting repairable SLAP lesions with all LRs close to one. The compression rotation test had the best LR for both definitions of disease (SLAP tear present = 1.8 and SLAP repaired = 1.67). There was no optimal combination of tests for diagnosing repairable SLAP lesions, with at least two tests positive providing the best combination of measurement properties (sensitivity 46.1% and specificity 64.7%). Conclusion Our study demonstrates that the physical examination tests for SLAP lesions are poor diagnostic indicators of disease. Performing a combination of tests will likely help, although the magnitude of the improvement is minimal. These authors caution clinicians placing confidence in the physical examination tests for SLAP lesions rather we suggest that clinicians rely on diagnostic imaging to confirm this diagnosis.

MONOCRYL and DERMABOND vs Staples in Total Hip Arthroplasty Performed Through a Lateral Skin Incision: A Randomized Controlled Trial Using a Patient-Centered Assessment Tool.

BACKGROUND: There are various possible methods of skin closure in total hip arthroplasty (THA) through a lateral skin incision. The cost and time required for each can vary between techniques. The objective of this study was to determine whether there is a difference in patient and surgeon rating of scar outcome using a combination of subcuticular suture and skin adhesive (subcuticular MONOCRYL and DERMABOND [SMD]) vs staples for skin closure after THA. METHODS: Patients undergoing THA were recruited from a university hospital. Patients were randomized to staples or SMD. Patient and Observer Scar Assessment Scale data were collected postoperatively. In addition, visual analog scale pain scores, wound drainage, length of stay, time to closure, and total cost were collected. RESULTS: One hundred twenty-nine patients were available for final analysis. There was no significant difference in Patient and Observer Scar Assessment Scale scores at 6 weeks or 3 months (P = .71). There was no difference in visual analog scale pain scores (P = .64, P = .49). The staple group had a higher rate of discharge on postoperative days 1 and 3 (P < .001, P < .001) but had a 1.6-minute shorter time of closure (P < .001). There was no significant difference in length of stay or total cost (P = .5). CONCLUSION: Although there are some small initial advantages to each method of skin closure, there is little difference in scar outcome when comparing SMD and staples.

The rotator cuff quality-of-life index predicts the outcome of nonoperative treatment of patients with a chronic rotator cuff tear.

BACKGROUND: Chronic rotator cuff tears are prevalent and can be disabling. The existing literature is unclear regarding the effectiveness of nonoperative treatment. The purposes of this study were to determine whether the outcome of nonoperative treatment can be predicted on the basis of the presenting clinical characteristics and whether the outcome achieved at three months after treatment can be maintained at two years. METHODS: The prospective cohort included ninety-three patients with a documented chronic full-thickness rotator cuff tear. Patients underwent a three-month supervised program of nonoperative treatment and were then evaluated by an orthopaedic surgeon. The treatment outcome was defined as a success if surgical treatment was no longer deemed appropriate by both patient and surgeon because the patient had improved considerably and was predominantly asymptomatic. The outcome was defined as a failure if the patient elected to have surgery after failing to improve and remaining symptomatic. The presenting clinical characteristics that were analyzed included age, sex, smoking status, hand dominance, duration of symptoms, onset (traumatic etiology or insidious onset), shoulder motion, external rotation strength, tear size as documented by ultrasonography or magnetic resonance imaging, and the Rotator Cuff Quality-of-Life Index (RC-QOL). RESULTS: Seventy (75%) of the patients were successfully treated. Logistic regression analysis showed that the baseline RC-QOL score was a significant predictor of outcome (p = 0.017). Eighty-nine percent of patients maintained their three-month outcome at two years of follow-up. CONCLUSIONS: The RC-QOL was predictive of the outcome of nonoperative treatment of patients with a chronic full-thickness rotator cuff tear. Patients in whom the nonoperative treatment was deemed successful at the conclusion of three months of treatment had a very high chance of ongoing success at two years after the initiation of treatment.

Economic evaluation of web-based compared with in-person follow-up after total joint arthroplasty.

BACKGROUND: We previously demonstrated the feasibility and clinical effectiveness of a web-based assessment following total hip or total knee arthroplasty. The purpose of the present study was to conduct an economic evaluation to compare a web-based assessment with in-person follow-up. METHODS: Patients who had undergone total joint arthroplasty at least twelve months previously were randomized to complete a web-based follow-up or visit the clinic for the usual follow-up. We recorded travel costs and time associated with each option. We followed patients for one year after the web-based or in-person follow-up evaluation and documented any resource use related to the joint arthroplasty. We conducted cost analyses from the health-care payer (Ontario Ministry of Health and Long-Term Care) and societal perspectives. All costs are presented in 2012 Canadian dollars. RESULTS: A total of 229 patients (118 in the web-based group, 111 in the usual-care group) completed the study. The mean cost of the assessment from the societal perspective was $98 per patient for the web-based assessment and $162 per patient for the usual method of in-person follow-up. The cost for the web-based assessment was significantly lower from the societal perspective (mean difference, $-64; 95% confidence interval [CI], $-79 to $-48; p < 0.01) and also from the health-care payer perspective (mean difference, $-27; 95% CI, $-29 to $-25; p < 0.01). CONCLUSIONS: The web-based follow-up assessment had a lower cost per patient compared with in-person follow-up from both societal and health-care payer perspectives.

Clinical Assessment of Physical Examination Maneuvers for Rotator Cuff Lesions.

BACKGROUND: Shoulder pain and disability pose a diagnostic challenge for clinicians owing to the numerous causes that exist. Unfortunately, the evidence in support of most clinical tests is weak or absent. PURPOSE: To determine the diagnostic validity of physical examination maneuvers for rotator cuff lesions. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 1. METHODS: Consecutive shoulder patients recruited for this study were referred to 2 tertiary orthopaedic clinics. A surgeon took a thorough history and indicated his or her certainty about each possible diagnosis. A clinician performed the physical examination for diagnoses where uncertainty remained. Arthroscopy was considered the reference standard for patients who underwent surgery, and MRI with arthrogram was considered the reference for patients who did not. The sensitivity, specificity, and likelihood ratios were calculated to investigate whether combinations of the top tests provided stronger predictions of the presence or absence of disease. RESULTS: There were 139 participants. None of the tests were highly sensitive for diagnosing rotator cuff tears or tendinosis. Tests for subscapularis tears were all highly specific. No optimal combination of tests improved the ability to correctly diagnose rotator cuff tears. Closer analysis revealed the internal rotation and lateral rotation lag sign did not improve the ability to diagnose subscapularis or supraspinatus tears, respectively, although the lateral rotation lag sign demonstrated a discriminatory ability for tear size. CONCLUSION: No test in isolation is sufficient to diagnose a patient with rotator cuff damage. A combination of tests improves the ability to diagnose damage to the rotator cuff. It is recommended that the internal rotation and lateral rotation lag signs be removed from the gamut of physical examination tests for supraspinatus and subscapularis tears.

Feasibility, effectiveness and costs associated with a web-based follow-up assessment following total joint arthroplasty.

The purpose of this study was to assess the feasibility, effectiveness and costs of a web-based follow-up compared to in-person assessment following primary total hip or total knee arthroplasty. Patients who were at least 12 months postoperative were randomized to follow-up method. We excluded patients who had revision surgery, osteolysis, complications or identified radiographic issues. 229 patients (118 Web, 111 in-person) completed the study. There were no patients who had an issue missed by the web-based follow-up. Patients in the web-based group travelled less (28.2km vs 103.7km, (P<0.01)), had lower associated costs ($10.45 vs $21.36, (P<0.01)) and took less time to complete (121.7min web vs 228.7min usual). Web-based follow-up is a feasible, clinically effective alternative with lower associated costs than in-person clinic assessment.

The average cost of pressure ulcer management in a community dwelling spinal cord injury population.

Pressure ulcers (PUs) are a common secondary complication experienced by community dwelling individuals with spinal cord injury (SCI). There is a paucity of literature on the health economic impact of PU in SCI population from a societal perspective. The objective of this study was to determine the resource use and costs in 2010 Canadian dollars of a community dwelling SCI individual experiencing a PU from a societal perspective. A non-comparative cost analysis was conducted on a cohort of community dwelling SCI individuals from Ontario, Canada. Medical resource use was recorded over the study period. Unit costs associated with these resources were collected from publicly available sources and published literature. Average monthly cost was calculated based on 7-month follow-up. Costs were stratified by age, PU history, severity level, location of SCI, duration of current PU and PU surface area. Sensitivity analyses were also carried out. Among the 12 study participants, total average monthly cost per community dwelling SCI individual with a PU was $4745. Hospital admission costs represented the greatest percentage of the total cost (62%). Sensitivity analysis showed that the total average monthly costs were most sensitive to variations in hospitalisation costs.

Qualiveen, a urinary-disorder specific instrument: 0.5 corresponds to the minimal important difference.

OBJECTIVE: This study assessed the interpretability of changes in Qualiveen, a specific health-related quality-of-life (HRQOL) questionnaire for urinary disorders (UD) in multiple sclerosis (MS) patients. Qualiveen has 30 items focusing on four aspects of patients' lives related to their urinary problems: bother with limitations (nine items), frequency of limitations (eight items), fears (eight items), and feelings (five items). Response options are framed as 5-point Likert-type scales, and scores on each domain range from 0 to 4. STUDY DESIGN AND SETTING: One hundred twenty-one MS patients with UD completed Qualiveen at baseline and 2-10 weeks later. At the second visit, patients also made global ratings of change in urinary HRQOL (GRC) with a 15-point scale from -7 to +7. We addressed the validity of GRC by examining its relationships with pre- and post-Qualiveen scores and determined the mean change in score on each Qualiveen domain associated with small, moderate, and large changes in the corresponding GRC. RESULTS: The correlation of the change score with the corresponding GRC was substantially stronger than the correlation with either pre- or post-Qualiveen score, establishing the validity of the GRC. In all domains, a within-patient change in Qualiveen score of approximately 0.5 (range: 0.36-0.72) represents the minimal important difference. A change in score of approximately 0.7 corresponds to a moderate change in quality of life (range: 0.55-0.86). CONCLUSIONS: These estimates will help in interpreting the results of subsequent studies that use Qualiveen to examine the impact of interventions designed to improve urinary-specific HRQOL.

Patients can provide a valid assessment of quality of life, functional status, and general health on the day they undergo knee surgery.

BACKGROUND: In the interest of efficiency, investigators often offer participants in surgical trials the option of completing baseline assessments on the day of surgery. The emotional affects of this day may, however, increase bias or random error. We studied the validity and reliability of collecting subjective ratings of health on the day of surgery. METHODS: One hundred and seventy-seven patients undergoing anterior cruciate ligament reconstruction and/or knee arthroscopy completed quality-of-life, functional status, and general health instruments at four weeks preoperatively, on the day of surgery, and one year postoperatively. We evaluated results with use of three conceptual frameworks: (1) that ratings provided four weeks preoperatively provide a gold standard for preoperative ratings, (2) that there is no gold standard for preoperative ratings and that, if valid, ratings on the day of surgery should be highly correlated with ratings at four weeks preoperatively and moderately and similarly correlated with ratings at one year postoperatively, and (3) that ratings provided four weeks preoperatively and on the day of surgery are measuring identical constructs and should therefore show high reliability. RESULTS: Most patients (97%) had a chronic injury as the interval between the injury and surgery was more than ninety days. Data collected on the day of surgery demonstrated high predictive validity with data collected within one month before surgery. There was no significant heterogeneity between variances for data collected four weeks preoperatively and on the day of surgery. The correlation between data collected on the day of surgery and four weeks preoperatively was moderate to high (range, 0.64 to 0.93), and the correlation between preoperative ratings and the one-year postoperative ratings was moderate (range, 0.40 to 0.59) across all instruments. Agreement between the ratings provided four weeks preoperatively and on the day of surgery was excellent (intraclass correlation coefficient, 0.64 to 0.91), and the standard error of measurement was small across instruments. CONCLUSIONS: In the treatment of chronic knee injuries, patients can accurately rate their quality of life, general health, and functional status on the day on which they undergo surgery.

Complementary and alternative medicine use in patients with fractures.

Complementary and alternative medicine (CAM) encompasses dietary supplements, herbs, homeopathic medicines, and other modalities. In light of prevalent CAM use, patient interest, increasing CAM expenditures, and possible interactions with traditional treatments or healing we identified the following in patients with fractures: prevalence of CAM use, the amount of money patients are spending on CAMs, and the number of patients who disclose CAM use to their orthopaedic surgeon and the reasons for withholding disclosure. Factors associated with CAM use were evaluated. Of the 322 patients with fractures surveyed, 35% were using CAMs. Of the patients using CAMs, 50% spent more than $25 per month. Fifty-five percent of the patients using CAMs had not discussed their CAM use with their orthopaedic surgeon citing "it was not an important issue to discuss." Factors associated with CAM use included level of education (odds ratio, 2.5; 95% confidence interval, 1.4-4.7) and psychiatric disorders (odds ratio, 2.5; 95% confidence interval, 1.3-5.0). To avoid possible interactions with traditional treatments and to identify side effects, surgeons should ask patients with fractures about CAM use in an unbiased fashion, as most patients will not voluntarily disclose their use.

Incorporating patient preferences into orthopaedic practice: should the orthopaedic encounter change?

The issues concerning treatment decision-making are that often options for treatment lead to uncertain outcomes (benefits and risks) at the individual patient level and that both patients and physicians might value these outcomes differently. There are three main approaches commonly used to describe treatment decision-making including paternalistic, shared and informed decision-making. The challenge and responsibility of physicians is to effectively communicate to patients that they should feel welcome to participate in decision-making through whichever approach seems suitable to them. Changes in laws governing the ethics of medical practice mandate a more comprehensive decision-making tactic requiring a two-way flow of information between patient and physician. The key to information exchange lies in evoking patient preferences by informing the patient of the benefits and risks associated with each treatment option. Decision aids have been developed in a variety of forms to facilitate this transfer of information about available treatment alternatives in as unbiased fashion as possible. We believe that treatment options presented should include not only those available by the particular physicians at that institution but also those available at outside institutions and within other healthcare systems. We discuss barriers for physicians who wish to encourage patient participation such as the power differential that exists between patients and physicians, factors related to health policy, and those unique to surgery. We believe that investigation is necessary to understand how the differences between types of medical practices, or even within a medical field, will influence the importance that patients attach to having their values and preferences considered during treatment decision-making and to evaluate how this importance changes as the severity of adverse events associated with treatment outcomes changes. We feel that it is important for physicians and surgeons to begin to think about these issues and how they might investigate potential resolutions for incorporating patient values and sharing their own preferences for treatment options with their patients during the orthopaedic encounter.

The influence of display and statistical factors on the interpretation of metaanalysis results by physicians.

OBJECTIVE: The objective of this study was to determine the extent to which various factors affect the interpretation of metaanalytic results by physicians. STUDY DESIGN: A sample of 120 physicians, selected from The Royal College of Physicians and Surgeons of Canada (RCPSC), was randomly assigned to 1 of 6 groups (n = 20) created from a combination of 3 summary measures and 2 levels of disease severity. The intervention consisted of a written scenario and 4 individual displays of metaanalyses (M-A), each followed by questions related to the interpretation of results of M-A. Two final questions examined statistical familiarity/proficiency with the summary measures used. DATA ANALYSIS: Analyses of variance examined main effects and interactions among 4 factors: summary measure, disease severity, effect size, and statistical consistency of the studies comprising the metaanalysis. Two outcomes were examined: interpretation of the treatment effect and confidence in the interpretation of the treatment effect. PRINCIPAL FINDINGS: Physicians were more likely to favor treatment when the results of the primary randomized, controlled trials (RCTs) were statistically homogeneous (P = 0.001) and when the overall effect size was large (P = 0.001). Also, physicians were more likely to be confident when the results were homogeneous (P = 0.001) and when effect size was large (P = 0.000). Interactions also revealed that the effect of statistical consistency of contributing to RCTs was greatest when data were presented as risk difference for treatment outcome (P = 0.026) and when effect size was small (P = 0.000). CONCLUSIONS: The interpretation of metaanalytic displays is influenced by the overall effect size of M-A, the statistical consistency of the contributing RCTs, and interactions of these factors with display factors.