Use of patient-reported global assessment measures in clinical trials of chronic pain treatments: ACTTION systematic review and considerations

Establishing clinically meaningful changes in pain experiences remains important for clinical trials of chronic pain treatments. Regulatory guidance and pain measurement initiatives have recommended including patient-reported global assessment measures (eg, Patient-Global Impression of Change [PGIC]) to aid interpretation of within-patient differences in domain-specific clinical trial outcomes (eg, pain intensity). The objectives of this systematic review were to determine the frequency of global assessment measures inclusion, types of measures, domains assessed, number and types of response options, and how measures were analyzed. Of 4172 abstracts screened across 6 pain specialty journals, we reviewed 96 clinical trials of chronic pain treatments. Fifty-two (54.2%) studies included a global assessment measure. The PGIC was most common (n = 28; 53.8%), with relatively infrequent use of other measures. The majority of studies that used a global assessment measure (n = 31; 59.6%) assessed change or improvement in an unspecified domain. Others assessed overall condition severity (n = 9; 17.3%), satisfaction (n = 8; 15.4%), or overall health status/recovery (n = 5; 9.6%). The number, range, and type of response options were variable and frequently not reported. Response options and reference periods even differed within the PGIC. Global assessment measures were most commonly analyzed as continuous variables (n = 24; 46.2%) or as dichotomous variables with positive categories combined to calculate the proportion of participants with a positive response to treatment (n = 18; 34.6%). This review highlights the substantial work necessary to clarify measurement and use of patient global assessment in chronic pain trials and provides short- and long-term considerations for measure selection, reporting and analysis, and measure development.