Can End-of-day reports replace momentary assessment of pain and fatigue?

Abstract

This study evaluated the ability of end-of-day (EOD) ratings to accurately reflect momentary (EMA) ratings on 10 widely used pain and fatigue items. Rheumatology patients (n = 105) completed >or=5 randomly scheduled EMA assessments of each item per day as well as EOD ratings. Correlations were high between EOD and EMA ratings of the 5 pain items (r = .90 to .92) and somewhat lower for the 5 fatigue/energy items (r = .71 to .86). To examine the ability of EOD ratings to represent 1 week of EMA ratings, 7 EOD ratings were averaged and correlated with EMA (r >or= .95 for pain items, r = .88 to .95 for fatigue/energy items). Further, averaging only 3 to 5 EOD ratings achieved very high correlations with 1 week of EMA ratings. Within-subject correlations of EOD with mean daily EMA across 7 days confirmed patients' ability to provide daily ratings that accurately reflect their day-to-day variation in symptom levels. These EOD results were compared to traditional recall ratings collected in the same protocol. It was concluded (1) that EOD ratings were a better representation of EMA than were recall ratings, and (2) that EOD ratings across a reporting period can replace EMA for studies targeting average levels of pain or fatigue.

Perspective: This study in chronic pain patients demonstrated that end-of-day ratings of pain are highly accurate representations of average levels of pain experience across a day; ratings of fatigue were somewhat less accurate, though still at a level that would be valid.

Figure 1

The black diamond is the correlation of the average of 7 EOD ratings with the average of the week’s EMA ratings. The open diamond represents the pooled average of the 7 correlations between EOD ratings and corresponding mean EMA ratings for that day, the error bars denote the range in correlations. The x is the pooled within-subject correlation of EOD and daily averages of EMA reports across the 7days. EMA averages are treated as latent variables.

Figure 2

Estimated correlations of one-week average momentary symptom levels (mean EMA, treated as a latent variable) with the average of EOD reports, as a function of the number of EOD reports (1 to 7) being averaged. Correlations are based on the Spearman-Brown formula, with correction for finite sampling (maximum of 7 EOD day reports in a week).