Does pain intensity predict a poor opioid response in cancer patients?

The aim of this study was to test the hypothesis that initial pain intensity is not a predictive factor of poor opioid response in advanced cancer patients, as suggested by a recent work.

A secondary analysis of one-hundred-sixty-seven patients referred for treatment of cancer-related pain was conducted. Pain intensity at admission was recorded and patients were divided in three categories of pain intensity: mild, moderate and severe. Patients were offered a treatment with opioid dose titration, according to department policy. Data regarding opioid doses and pain intensity were collected after dose titration was completed. Four levels of opioid response were considered: (a) good pain control, with minimal opioid escalation and without relevant adverse effects; (b) good pain control requiring more aggressive opioid escalation, for example doubling the doses in four days; (c) adequate pain control associated with the occurrence of adverse effects; (d) poor pain control with adverse effects.

Seventy-six, forty-four, forty-one and six patients showed a response a, b, c, and d, respectively. No correlation between baseline pain intensity categories and opioid response was found. Patients with response 'b' and 'd' showed higher values of OEImg.

Baseline pain intensity does not predict the outcome after an appropriate opioid titration. It is likely that non-homogeneous pain treatment would have biased the outcome of a previous work.