Accuracy of using Diagnosis Procedure Combination administrative claims data for estimating the amount of opioid consumption among cancer patients in Japan.

Objective: The state of opioid consumption among cancer patients has never been comprehensively investigated in Japan. The Diagnosis Procedure Combination claims data may be used to measure and monitor opioid consumption among cancer patients, but the accuracy of using the Diagnosis Procedure Combination data for this purpose has never been tested.
Methods: We aimed to ascertain the accuracy of using the Diagnosis Procedure Combination claims data for estimating total opioid analgesic consumption by cancer patients compared with electronic medical records at Aomori Prefectural Central Hospital. We calculated percent differences between estimates obtained from electronic medical records and Diagnosis Procedure Combination claims data by month and drug type (morphine, oxycodone, fentanyl, buprenorphine, codeine and tramadol) between 1 October 2012 and 30 September 2013, and further examined the causes of discrepancy by reviewing medical and administrative charts between April and July 2013.
Results: Percent differences varied by month for drug types with small prescription volumes, but less so for drugs with larger prescription volumes. Differences also tended to diminish when consumption was compared for a year instead of a month. Total percent difference between electronic medical records and Diagnosis Procedure Combination data during the study period was -0.1% (4721 mg per year per hospital), as electronic medical records as baseline. Half of the discrepancy was caused by errors in data entry.
Conclusion: Our study showed that Diagnosis Procedure Combination claims data can be used to accurately estimate opioid consumption among a population of cancer patients, although the same conclusion cannot be made for individual estimates or when making estimates for a group of patients over a short period of time.
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