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Breakthrough pain in community-dwelling patients with cancer pain and noncancer pain, part 1: prevalence and characteristics.

BACKGROUND
Most breakthrough pain (BTP) studies assess patients with advanced cancer or those receiving inpatient care. Studies in noncancer populations are limited to surveys of pain clinics and patients with other advanced diseases. To better understand BTP, data are needed from less selected populations.


AIM
The aim of this study was to evaluate BTP in opioid-treated ambulatory patients with chronic cancer or noncancer pain treated in community practices.


METHODS
Primary care physicians or community-based oncologists recruited a convenience sample for a cross-sectional study of BTP at 17 sites in the United States. Physicians could not be pain specialists. Patients were eligible if they had any type of pain for > or = 3 months and were receiving an opioid drug on a regular basis that controlled the pain. The patients responded to a structured interview comprising items that assessed the baseline pain and items that assessed BTP, if present.


RESULTS
In total, 355 patients were screened, 191 were eligible and 177 (93 percent) provided data for analysis. Seventy-eight patients had cancer pain and 99 had noncancer pain. Patients with cancer were older (mean +/- SD age 61.3 +/- 11.2 years vs 51.4 +/- 13.6 years, p < 0.001), and patients without cancer had more neuropathic pain (21 vs 12 percent, p < 0.05) and a longer pain duration (median 3.5 vs 1 years, p < 0.001). BTP occurred in 33 percent with cancer and 48 percent with noncancer pain (p = 0.042). BTP did not vary by diagnosis, but neuropathic pain was more common in those with BTP (27 vs 10 percent, p < 0.001). In patients with and without cancer, the median daily number of episodes was 1, the median time to maximum pain was 1-2 minutes, and the median duration was 45-60 minutes. There were fewer BTP precipitants in the patients with cancer (46 vs 80 percent of pains, p < 0.05), and they had less predictable pain (p < 0.05).


CONCLUSIONS
The prevalence of BTP among community-dwelling patients is lower than that found in prior studies of more selected populations. BTP is more prevalent among patients with noncancer pain than patients with cancer pain, and although there are many similarities, some differences may be relevant to treatment strategies.