Background: Pain control is one of the most important goals of end-of-life care, and the use of opioids for this purpose is extremely common in hospice settings. However, it is unknown how many of the patients require high dose morphine (HDM, >299 mg/day of oral morphine equivalent), what the characteristics of these patients are, and whether the use of HDM might affect their survival.

Methods: The authors retrospectively studied the medical records of all 651 inpatients hospitalized at their center between January 1996 and December 1997. Information was collected regarding demographic parameters, medical diagnosis, pain mechanism, morphine dosage, use of rescue doses in addition to regular doses, use of coanalgesics and adjuvant treatments, and survival time in the hospice setting as associated with morphine dosage.

Results: The authors identified 453 patients (69.58%) who received morphine for pain relief, of whom 55 (12.14%) needed more than 299 mg/day. Morphine dosage was negatively associated with age (r = -0.35, P = 0.01). Male patients and nonwhite patients required slightly higher dosages than others. Primary breast and genitourinary cancers, as well as metastases to bone and spinal diseases, were associated with higher morphine dosages. Statistical analysis indicated a positive correlation between the log maximum of morphine dosage and the total number of rescue dosages (r = 0.307, P = 0.025). The median survival of patients on HDM was 15.6 days and did not differ from the survival of patients taking a lower dosage.

Conclusions: A fairly strong correlation exists between morphine dosage and some clinicodemographic data. No significant dose-limiting adverse effects were observed, suggesting a high clinical safety profile. High morphine dosage does not affect patient survival. Awareness of the dosage factors will improve our ability to treat and predict probable HDM dosage, thus shortening the period until pain relief is reached.