The paucity of effects in community trials: Is secular trend the culprit?

Background The most recent major U.S. trials that evaluated community-level programs to influence risk factors and health behaviors identified secular trends in the risk factors and health behaviors among the factors that mig ht have limited community-level effects. The research reported in this pape r uses data from one of the trials to examine the secular trend explanation directly. Methods. Data from the 22-community Community Intervention Trial for Smokin g Cessation (COMMIT) were analyzed to test a hypothesis based on secular tr end reasoning: program effects for smoking prevalence Fs ere larger for tre atment communities matched to control communities with small declines in sm oking than in treatment communities matched to control communities with lar ger declines in smoking. Results. Consistent with the secular trend explanation, program effects wer e larger when control communities had relatively small declines in smoking prevalence. Conclusions. The findings suggest that secular trends masked community-leve l program effects in COMMIT. (C) 1999 American Health Foundation and Academ ic Press.