Background: Ecological momentary assessment (EMA) offers a highly valid strategy to assess everyday functioning in people with severe mental illness. Adherence is generally good, but several questions regarding the impact of study length, daily density of sampling, and symptom severity on adherence remain.
Methods: EMA adherence in two separate studies was examined. One sampled participants with schizophrenia (n=106) and healthy controls (n=76) 7 times per day for 7 days and the other sampled participants with schizophrenia (n=104) and participants with bipolar illness (n=76) 3 times per day for 30 days. Participants were asked where they were, who they were with, what they were doing and how they were feeling in both studies. The impact of rates of very early adherence on eventual adherence was investigated across the samples, and adherence rates were examined for associations with mood state and most common location when answering surveys.
Results: Median levels of adherence were over 80% across the samples, and the 10th percentile for adherence was approximately 45% of surveys answered. Early adherence predicted study-long adherence quite substantially in every sample. Mood states did not correlate with adherence in the patient samples and being home correlated with adherence in only the bipolar sample.
Implications: Adherence was quite high and was not correlated with the length of the study or the density of sampling per study day. There was a tendency for bipolar participants who were more commonly away from home to answer fewer surveys but overall adherence for the bipolar patients was quite high. These data suggest that early nonadherence is a potential predictor of eventual nonadherence and study noncompletion.
Keywords: EMA completion rates; bipolar disorder; ecological momentary assessment; schizophrenia; survey adherence.