Pain assessment in patients with low back pain: comparison of weekly recall and momentary electronic data

Electronic data collection for monitoring pain has become increasingly popular in clinical research. Past research has shown that electronic diaries improve the timeliness of receipt of data, contribute to higher rates of compliance, and are preferred by patients over paper diaries, and this research suggests that electronic diaries that capture current pain at the moment of reporting result in more reliable ratings than recalled pain ratings. This study compared differences of momentary pain intensity ratings on an electronic visual analog scale (VAS) with weekly recalled pain on a 0 to 10 scale. We asked 21 patients with chronic low back pain to monitor their current pain at least once a day by using a VAS for up to 1 year with a palmtop computer. They were also called once a week and asked to rate their recalled weekly pain orally on a numeric scale from 0 to 10. Patients entered data electronically on average 357 times, for an average of 7.8 times a week. We found that (1) weekly recalled pain agreed highly (r > .90) with averaged momentary pain assessments, (2) neither frequency of electronic monitoring nor variability in momentary pain ratings (high standard deviations) contributed to degree of agreement between momentary and recalled pain, and (3) a ceiling effect was observed in VAS pain ratings as compared with numeric pain ratings. These findings suggest that, among many individuals, weekly recalled pain might be just as useful as momentary data collected through electronic data entry.

Some believe that remembered pain is problematic because of recall bias and that data from frequent momentary pain ratings with electronic diaries are more valid. This study demonstrates that recalled pain is as valid as momentary data for many patients.