To examine daily positive affective disturbance in the context of negative affect (NA) and pain among patients with fibromyalgia (FM) to determine a) if FM patients experience a deficit in daily positive affect (PA) relative to osteoarthritis (OA) patients; b) if FM patients differ from OA patients in the day-to-day relations of PA and NA; and c) if patients diagnosed with both OA and FM differ from patients with either OA-only or FM-only with respect to major outcomes.
A total of 260 women with physician-diagnosed OA (n = 106), FM (n = 53), or OA/FM (n = 101) completed a 30-day electronic diary. Participants were assessed once daily on levels of PA, NA, and pain.
Multilevel models indicated that FM patients had less overall PA than OA patients and exhibited a stronger inverse PA-NA relation. Analyses further suggest that the OA/FM group may have been the most impaired of the three included in our study. This group was responsible for a lagged effect of PA on both affects, whereby high PA days resulted in low next-day PA and high next-day NA.
FM patients exhibit a PA disturbance compared with OA patients. This disturbance is reflected by an overall deficit in PA and an inability to sustain PA in the face of pain and NA. Patients with both OA and FM may represent a subgroup of FM that is at particular risk for dysregulation of PA.