Reactive measures (measures that change the phenomenon assessed) cause problems in interpreting any changes observed. This study examined whether electronic daily diary measures of pain, activity interference, mood, and pain beliefs were reactive in terms of both observable data and patient-reported effects. Patients with chronic temporomandibular disorder pain (N = 71, 86% female) completed electronic diaries 3 times daily for approximately 2 weeks and subsequently reported perceived effects on symptom-related variables. Seventy-three percent of patients reported that the assessment affected their pain, whereas 51%, 45%, and 39% thought that it affected their daily activities, mood, and beliefs, respectively. In contrast, there was little objective evidence of reactivity as observed in the electronic diary ratings; changes over 14 days were small (eg, predicted changes on 0 to 10 scales: positive mood, .1; pain, -.3; perceived control, -.5) and not statistically significant. Subjective reactivity was generally not significantly related to objective reactivity. The data suggest that patients view daily assessment as having positive and negative effects on pain-related variables, but pain-related measures do not show reactive effects.
Perspective: Electronic daily diary assessment methods hold the potential to increase knowledge concerning patients' experiences with pain and sequential relations between pain-related variables, but only if the measurement process is nonreactive. This study provides evidence that electronic diary assessment of pain-related variables is nonreactive.