Comparison of 7-day recall and daily diary reports of COPD symptoms and impacts.

OBJECTIVE: Patient reporting of symptoms in a questionnaire with a 7-day recall period was expected to differ from symptom reporting in a 7-day symptom diary on the basis of cognitive theory of memory processes and several studies of symptoms and health behaviors.
METHODS: A total of 101 adults with chronic obstructive pulmonary disease (COPD) completed a daily diary of items measuring symptoms and impacts of COPD for 7 days, and on the seventh day they completed a questionnaire of the same items with a 7-day recall period. The analysis examined concordance of 7-day recall with summary descriptors of the daily responses, examined the magnitude and covariates (patient characteristics and response patterns) of the difference between 7-day recall and mean of daily responses, and compared the discriminant ability and ability to detect change of 7-day recall and mean of daily responses.
RESULTS: A 7-day recall was moderately concordant with the mean and maximum of daily responses and was 0.34 to 0.50 SDs higher than the mean of daily responses. Only the weekly report itself was a covariate of the difference. The discriminant ability and ability to detect change were equivalent.
CONCLUSIONS: In measuring the weeklong experience of COPD symptoms and impacts on groups of patients, the 7-day recall scores were higher than the daily diary scores, but equivalent in detecting change over time.