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Pilot studies test the feasibility of methods and procedures to be used in larger-scale studies. Although numerous articles describe guidelines for the conduct of pilot studies, few have included specific feasibility indicators or strategies for evaluating multiple aspects of feasibility. Additionally, using pilot studies to estimate effect sizes to plan sample sizes for subsequent randomized controlled trials has been challenged; however, there has been little consensus on alternative strategies. METHODS: In Section 1, specific indicators (recruitment, retention, intervention fidelity, acceptability, adherence, and engagement) are presented for feasibility assessment of data collection methods and intervention implementation. Section 1 also highlights the importance of examining feasibility when adapting an intervention tested in mainstream populations to a new more diverse group. In Section 2, statistical and design issues are presented, including sample sizes for pilot studies, estimates of minimally important differences, design effects, confidence intervals and non-parametric statistics. An in-depth treatment of the limits of effect size estimation as well as process variables is presented. Tables showing confidence intervals around parameters are provided. With small samples, effect size, completion and adherence rate estimates will have large confidence intervals. CONCLUSION: This commentary offers examples of indicators for evaluating feasibility, and of the limits of effect size estimation in pilot studies. As demonstrated, most pilot studies should not be used to estimate effect sizes, provide power calculations for statistical tests or perform exploratory analyses of efficacy. It is hoped that these guidelines will be useful to those planning pilot/feasibility studies before a larger-scale study.

Author(s): Gill, Thomas M; Bhasin, Shalender; Reuben, David B; Latham, Nancy K; Araujo, Katy; Ganz, David A; Boult, Chad; Wu, Albert W; Magaziner, Jay; Alexander, Neil; Wallace, Robert B; Miller, Michael E; Travison, Thomas G; Greenspan, Susan L; Gurwitz, Jerry H; Rich, Jeremy; Volpi, Elena; Waring, Stephen C; Manini, Todd M; Min, Lillian C; Teresi, Jeanne; Dykes, Patricia C; McMahon, Siobhan; McGloin, Joanne M; Skokos, Eleni A; Charpentier, Peter; Basaria, Shehzad; Duncan, Pamela W; Storer, Thomas W; Gazarian, Priscilla; Allore, Heather G; Dziura, James; Esserman, Denise; Carnie, Martha B; Hanson, Catherine; Ko, Fred; Resnick, Neil M; Wiggins, Jocelyn; Lu, Charles; Meng, Can; Goehring, Lori; Fagan, Maureen; Correa-de-Araujo, Rosaly; Casteel, Carri; Peduzzi, Peter; Greene, Erich J | Abstract: Background/objectivesIn the Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) study, a multifactorial intervention was associated with a nonsignificant 8% reduction in time to first serious fall injury but a significant 10% reduction in time to first self-reported fall injury relative to enhanced usual care. The effect of the intervention on other outcomes important to patients has not yet been reported. We aimed to evaluate the effect of the intervention on patient well-being including concern about falling, anxiety, depression, physical function, and disability.DesignPragmatic cluster-randomized trial of 5,451 community-living persons at high risk for serious fall injuries.SettingA total of 86 primary care practices within 10 U.S. healthcare systems.ParticipantsA random subsample of 743 persons aged 75 and older.MeasurementsThe well-being measures, assessed at baseline, 12 months, and 24 months, included a modified version of the Fall Efficacy Scale, Patient-Reported Outcomes Measurement Information System (PROMIS) anxiety and depression scales, and Late-Life Function and Disability Instrument.ResultsParticipants in the intervention (n = 384) and control groups (n = 359) were comparable in age: mean (standard deviation) of 81.9 (4.7) versus 81.8 (5.0) years. Mean scores were similar between groups at 12 and 24 months for concern about falling, physical function, and disability, whereas the intervention group's mean scores on anxiety and depression were .7 points lower (i.e., better) at 12 months and .6 to .8 points lower at 24 months. For each of these outcomes, differences between the groups' adjusted least square mean changes from baseline to 12 and 24 months, respectively, were quantitatively small. The overall difference in means between groups over 2 years was statistically significant only for depression, favoring the intervention: -1.19 (99% confidence interval, -2.36 to -.02), with 3.5 points representing a minimally important difference.ConclusionsSTRIDE's multifactorial intervention to reduce fall injuries was not associated with clinically meaningful improvements in patient well-being.

Author(s): Hays, Ron D; Weech-Maldonado, Robert; Teresi, Jeanne A; Wallace, Steven P; Stewart, Anita L