Cancer breakthrough pain characteristics and responses to treatment at a VA medical center.

The purpose of this study is to analyze cancer breakthrough pain (BP) characteristics and how BP responds to conventional cancer pain management. Seventy-four cancer pain patients with worst pain severity >or=4 out of 10 completed the Brief Pain Inventory (BPI), Memorial Symptom Assessment Scale-Short Form, Functional Assessment Cancer Therapy and Breakthrough Pain Questionnaires (BPQ) at an initial interview. Agency for Health Care Policy and Research (AHCPR) cancer pain management guidelines were followed. Pain syndromes and morphine equivalent daily dose (MEDD) orally were determined. One-week follow-up assessments were obtained in 66 patients with BPI and BPQ. The BP characteristics were similar at both time points. On day 1, 52 patients (70%) had BP, and the BP was unpredictable in 30 patients (58%). The median time to worst BP severity was 3 min. Patients with BP had significantly higher worst pain (P<0.001). At week 1, the median MEDD doubled from 60 to 120 mg orally, and the number of patients who received adjuvant analgesics doubled from 31.1% (23 patients) on day 1 to 62.2% (41 patients). At week 1, 21 patients (32%) remained without BP, 21 patients (32%) were classified as BP responders and 24 patients (36%) were BP non-responders. The mean pain relief was similar for all three subgroups, i.e. around 80%. Compared to BP responders, BP non-responders had significantly higher worst pain (P<0.0001), average pain (P<0.004), and higher BPI interference parameters and shorter time to worst pain severity. The study confirmed the applicability of the BPQ to an US veteran population, and that pain management following the AHCPR guidelines is effective for a group of patients with cancer related BP. Underlying pain syndromes and the BP location may influence the response of BP to treatment. Patients with bone pain located in the spine, back, and pelvis may be at risk for resistant BP.