Factors influencing constipation in advanced cancer patients: a prospective study of opioid dose, dantron dose and physical functioning.

The relationship between opioid dose, dantron dose, bowel function and physical functioning (measured with the modified Barthel Index) was determined in a sample of 50 inpatients with advanced cancer. Data were collected prospectively from chart review and patient interviews one week after admission to allow for protocol-driven management of constipation to be established. Bowel scores were significantly reduced in 35 patients treated with opioids compared with 15 patients not treated with opioids. Within the opioid group, however, there was no relationship between opioid dose, bowel score, dantron dose or Barthel Index. Higher doses of dantron were associated with better physical functioning (but not opioid dose) suggesting that for any given dose of opioid, fitter patients were treated with larger doses of laxatives. Factors other than opioid dose and physical functioning may be more important in contributing to constipation in this group of patients. Less potent opioid drugs, such as codeine, are just as likely to cause constipation as more potent opioids.