Electronic momentary assessment in chronic pain I: psychological pain responses as predictors of pain intensity.

OBJECTIVES AND METHODS: Electronic momentary assessment was employed to substantiate the relevance of psychological functioning in chronic pain. More than 7,100 electronic diaries from 80 patients with varying IASP classified types of chronic pain served to investigate to what extent fear-avoidance, cognitive and spousal solicitous and punishing pain responses explained fluctuations in pain intensity and whether patients with pre-chronic, recently chronic and persistently chronic pain differed in this regard.
RESULTS: Psychological pain responses explained 40% of the total variance in pain intensity: almost 24% concerned pain variance that occurred between the CPD patients and 16% pertained to pain variance due to momentary differences within these patients. Separately tested fear-avoidance and cognitive responses each explained about 28% of the total pain variance, while spousal responses explained 9%. Catastrophizing emerged as the strongest pain predictor, followed by pain-related fear and bodily vigilance. Results did not differ with the duration of chronicity. DISCUSSION: Exaggerated negative interpretations of pain, and fear that movement will induce or increase pain strongly predicted CPD pain intensity. Spousal responses-assessed only when the spouse was with the patient who at that moment was in actual pain-may more strongly affect immobility due to pain than pain intensity per se (see part II of the study). The findings substantiate the importance of catastrophizing, fear and vigilance identified primarily in low back pain and extend this to other forms of chronic pain. The compelling evidence of momentary within-patients differences underscores that these must be accounted for in chronic pain research and practice.