In 2000, Schmidt, et. al., delved into the dynamics of attrition within an exercise program designed to enhance physical function in frail older individuals. With a focus on two distinct exercise modalities—class-based and self-paced—the study aimed to identify the reasons behind participant dropout and potential predictors of attrition.

The study enrolled 155 community-dwelling older individuals, averaging 77.4 years of age, with mild to moderate mobility challenges. The primary outcome measure was dropout, categorized as D0 for those leaving between baseline and the 3-month assessment, and D3 for those dropping out after the 3-month assessment.

Of the total participants, 36% (56 individuals) dropped out, with 31 discontinuing within the initial 3 months. Comparisons between the retained (R) and D0 groups revealed that the latter had a higher disease burden (P = .011), poorer self-perceived physical health (P = .014), slower usual gait speed (P = .001), and covered a shorter distance in the 6-minute walk (P<.001). No significant differences were found between the R and D3 groups.

Multinomial logistic regression analysis pinpointed the 6-minute walk (P<.001) and usual gait velocity (P<.001) as robust independent predictors of dropout. Controlling for other variables, adverse events post-randomization and 6-minute walk distance emerged as the most influential factors contributing to dropout. Interestingly, individuals assigned to self-paced exercise faced an increased risk of dropout.

The study highlighted baseline disparities between early dropouts and retained participants in terms of disease burden, physical function, and endurance. These findings suggest that such factors at the outset may serve as predictors for dropout. Recognizing these indicators pre-randomization could empower researchers to identify and implement targeted retention strategies, potentially reducing attrition rates in future studies.

Understanding the determinants of dropout is crucial to mitigate potential drawbacks, such as decreased subject heterogeneity, limited generalizability of study findings, and an incomplete grasp of exercise effects in this specific population. By addressing these challenges, researchers can enhance the robustness and applicability of their investigations, ultimately advancing our comprehension of exercise interventions for frail older adults.

Reference: Schmidt, J. A., Gruman, C., King, M. B., & Wolfson, L. I. (2000). Attrition in an exercise intervention: a comparison of early and later dropouts. Journal of the American Geriatrics Society, 48(8), 952-960.