Breakthrough pain: characteristics and impact in patients with cancer pain

Few surveys have been performed to define the characteristics and impact of breakthrough pain in the cancer population. In this cross-sectional survey of inpatients with cancer, patients responded to a structured interview (the Breakthrough Pain Questionnaire) designed to characterize breakthrough pain, and also completed measures of pain and mood (Memorial Pain Assessment Card (MPAC)), pain-related interference in function (Brief Pain Inventory (BPI)), depressed mood (Beck Depression Inventory (BDI)), and anxiety (Beck Anxiety Inventory (BAI)). Of 178 eligible patients, 164 (92.2%) met the criteria for controlled background pain. The median age was 50.6 years (range 26 to 77 years), 52% were men, and 80.6% were Caucasian. Tumor diagnoses were mixed, 75% had metastatic disease, 65% had pain caused directly by the neoplasm, and a majority had mixed nociceptive-neuropathic pain. The median Karnofsky Performance Status score was 60 (range 40 to 90). Eighty-four (51.2%) patients had experienced breakthrough pain during the previous day. The median number of episodes was six (range 1 to 60) and the median interval from onset to peak was 3 min (range 1 s to 30 min). Although almost two-thirds (61.7%) could identify precipitants (movement 20.4%; end-of-dose failure 13.2%), pain was unpredictable in a large majority (78.2%). Patients with breakthrough pain had more intense (P < 0.001) and more frequent (P < 0.01) background pain than patients without breakthrough pain. Breakthrough pain was also associated with greater pain-related functional impairment (difference in mean BPI, P < 0.001), worse mood (mood VAS, P < 0.05; BDI, P < 0.001), and more anxiety (BAI, P < 0.001). Multivariate analysis confirmed that breakthrough pain independently contributed to impaired functioning and psychological distress. These data confirm that cancer-related breakthrough pain is a prevalent and heterogeneous phenomenon. The presence of breakthrough pain is a marker of a generally more severe pain syndrome, and is associated with both pain-related functional impairment and psychological distress. The findings suggest the need for further studies of breakthrough pain and more effective therapeutic strategies. (C) 1999 International Association for the Study of Pain. Published by Elsevier Science B.V.