Special to DG News

NEW ORLEANS, LA -- February 21, 2003 -- Constipation is significantly more common in chronic pain patients prescribed oxycodone controlled-release (CR) compared with other treatments commonly used for chronic pain management, according to a retrospective claims analysis of a Medicaid database.

The results were released on February 20^th at the 19^th Annual Meeting of the American Academy of Pain Medicine.

Dr. Peter S. Staats, with Johns Hopkins Hospital in Baltimore, Maryland, and co-workers used claims data from the California Medicaid database during a recent 5-year period to determine the frequency of constipation in adult patients with malignant or non-malignant pain who had been treated for at least 3 months with one of three different long-acting opioids.

Overall, 601 patients had received transdermal fentanyl, 721 had received oxycodone CR, and 514 had received morphine sulfate CR.

The primary outcome variable was a primary or secondary International Classification of Diseases, Ninth Revision (ICD-9) diagnosis of constipation.

Results showed that crude rates of constipation were lower for patients receiving transdermal fentanyl -- 3.7% versus 6.1% for oxycodone CR and 5.1% for morphine sulfate CR.

Incidence density rates of constipation per year were 4.8% for transdermal fentanyl, 6.8% for oxycodone CR, and 5.5% for morphine CR. Incidence density describes new constipation events, accounting for the person/time at risk of developing this outcome during the study period. In this study, the researchers calculated incidence density by dividing new constipation cases by the total number of exposure days and calculating a yearly rate.

After controlling for confounding variables of race, rescue medication use, and number of days of opioid exposure, oxycodone CR was associated with a significantly higher risk of constipation (OR=1.78, p=0.0337) compared with transdermal fentanyl.

Morphine CR had a non-statistically significant higher risk of constipation relative to transdermal fentanyl.

Dr. Staats cautioned that the study has several potential limitations. For example, retrospective claims analyses may not reflect actual medication usage, he said. In addition, the data were derived from a Medicaid population and it may not be accurate to generalise to other patient populations.

He added that since the constipation outcome was defined by an ICD-9 code, most likely representing severe or unremitting constipation, the incidence cited in this study is most likely an underestimate of the overall constipation rate.

Janssen Pharmaceutical, Inc., of Titusville, New Jersey, sponsored the study.


[Study title: The Incidence of Constipation in Chronic pain Patients Taking Long-Acting Opioids]

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