Minimizing attrition in a long-term clinical trial of pediatric asthma

Abstract

Despite increased attention focused on the need to prevent patient attrition in long-term clinical trials, high dropout rates have threatened the success of numerous studies. To evaluate the disease, demographic, and psychological factors associated with missed visits and study dropout to help improve patient management in long-term clinical trials. Predictors of attrition were examined within the Childhood Asthma Management Program (CAMP), a large, multicenter clinical trial that followed up 1,041 children with asthma for 4 to 6 years. Eighty-two percent of patients attended all study visits. The tendency to miss visits was increased among older children with milder asthma, lower intellectual and social competence, and more symptoms of behavioral problems and emotional distress. Forty-two patients who missed 3 or more visits in a row and did not attend the final visit were considered study dropouts; these patients at baseline had milder asthma; lower cognitive, academic, and social competence skills; and more family conflict and distress than found among participants who remained in the study. The 49 children who had erratic attendance but did not drop out also had lower intellectual and academic skills and less family social support. The 4% dropout rate in CAMP was lower than reported in any previous long-term asthma trial. The findings of milder disease, decreased psychological resources, and increased distress in problem-attendance patients can assist in identifying patients who are at risk for missed visits or dropout during the trial either to block their entry into the trial or to focus efforts at maintaining their attendance once enrolled in the trial.