The validity of average 8-h pain intensity assessment in cancer patients

Aim of this study was to validate the use of subjective average pain assessment over an 8-h time period to evaluate cancer pain intensity. A sample of 95 consecutive cancer inpatients were asked to score on 0-10 numerical scales the intensity of their pain at hourly intervals, and then, at the 8th hour, to rate their average pain intensity over the last 8h. Agreement between the average of the 8 hourly measures (8hA) and the single patient-rated average (PA8h) was examined with the intraclass correlation coefficient (ICC) and the absolute difference (AD) between the two measurements. Associations between AD, gender, age older than 70, somatic pain, visceral pain, neuropathic pain, pain on movement and the presence of pain exacerbations during the 8-h period, were also examined. Average pain intensity scores were very similar with the two measurement schedules: 3.4 for 8hA and 3.7 for PA8h, with a median AD of 0.44 points. Only six patients (6.3%) showed ADs higher than 2 points. Also the ICC (0.85) showed a substantial agreement between the two schedules. Among the examined variables, gender, age over 70years and presence of pain exacerbations showed a significant association with the agreement level. Overall, our results support the validity of a subjective average pain measurement over 8-h period in cancer patients.