The difficulty with breakthrough pain

Eugene Becker, M.D.

Portenoy, R.K., Payne, D., Jacobsen, P. (1999). Breakthrough Pain: Characteristics and Impact in Patients with Cancer Pain. Pain, 81:129-134.

Cancer pain is difficult to characterize and assess. There is no survey available to quantify and compare pain between patients. In this article, Dr. Portenoy examines approaches that could effectively yield specific information about breakthrough pain.

Background pain (BP) is defined as pain experienced for more than half the waking days during the previous weeks, or if a fixed schedule opioid regimen had been used on more than half the days during the previous week. Patients were considered to have breakthrough pain if they reported background pain with one or more severe or excruciating episodes of pain during the past day.

1. To determine descriptive parameters for BP; and
2. To determine the difference in psychological and physical pain.

Results generated were descriptive statistics.

178 patients were divided into three groups: Background pain with no BP (Group 1); Background pain with BP (Group 2); and Background pain not well controlled. Statistics were generated from a comparison of Groups 1 and 2. The following surveys were used: Memorial Pain Assessment Card, Brief Pain Inventory, Beck Depression Inventory, Beck Anxiety Inventory; Karnofsky Performance Status Score. Breakthrough pain was assessed in terms of time between onset and peak intensity; its location, quality, and predictability, precipitating factors, and relief-providing factors.

Findings related to background pain: 64% were caused directly by neoplasm, while the remainder was related to neoplastic treatments. Both neuropathic and nociceptive features were present 52% of the time.

Findings related to breakthrough pain: Time from onset to peak was 1 second to 30 minutes, with a mean of 3 minutes. The predictability of breakthrough pain was: Never-48..2%; Sometimes-18,8%; Almost Always-10.6%, and Always-15.3%. Precipitants were movement 20.4%; end of dose-13.2%; others-28.1%; unsure-38.3%.

Breakthrough pain is widespread and difficult to treat. Severity and unpredictability of breakthrough pain and with which it usually occurs could compromise function and undermine the patient's sense of control. Higher levels of pain, functional impairment, and distress indicate inadequate treatment that is based on rescue dosing.

Most breakthrough pain reaches its peak at three minutes; however most oral medication reaches peak effect in 15-30 minutes. It contributes to dissatisfaction with pain control, and an increased total amount of rescue dose. A current calculation of the rescue dose is based on the total dose of baseline opioid (fixed percentage of baseline dose).

Recent studies with transmucosal fentanyl, which has a fast onset, suggests that better pain control is achieved by titration of the rescue dose, and not the fixed percentage of the baseline dose. In addition, the fact that patients with breakthrough pain gave higher levels of background pain and are on the same doses of opioids as patient without breakthrough pain, suggests that the increase in total baseline doses could be a solution to better pain control.

The strong part of this study is the fact that researchers were able to review a relatively large number of patients-178. Their findings that onset and precipitants of BP are important in the treatment of BP. In the future there should be more focus on characteristics of BP such as onset, duration, and character: for example, neuropathic or somatic.

Eugene Becker, M.D.
Pain Management Fellow, 1999-2000
Department of Anesthesiology and Pain Management
University of California, Davis