Impact of Iowa's Prescription Monitoring Program on Opioid Pain Reliever Prescribing Patterns: An Interrupted Time Series Study 2003-2014.

Objective: To evaluate the impact of Iowa's prescription monitoring program (PMP), implemented in 2009, on opioid pain reliever (OPR) prescribing patterns.

Methods: We conducted interrupted time series analyses using 2003-2014 health insurance claims from a private health insurer in Iowa. OPR prescriptions for all beneficiaries were included. Another data set included only OPR prescription for new opioid users required to have six months of insurance coverage. We evaluate four OPR prescribing patterns: 1) average daily dosage in morphine milligrams equivalents (MME), 2) MME per prescription, 3) average days' supply per prescription, and 4) prescription rate per 1,000 insured person-years. We examined confounding and effect measure modification of the relationship between PMP and prescribing patterns by age and sex.

Results: During the 12 years of follow-up, 1,512,388 insured Iowans contributed 6,169,634.92 person-years of follow-up. Of these, 505,274 patients filled 2,401,818 OPR prescriptions and 360,688 new OPR users filled as many first OPR prescriptions. The increasing trend of OPR prescription rates from 2003 to 2009 declined post-PMP. Similarly, there was a large decline in MME per day and MME per prescription. The OPR days' supply kept increasing post-PMP implementation, albeit at a slightly slower rate than pre-PMP implementation. There was no confounding by age and sex; however, we observed heterogeneity by age and sex; patients aged ≥50 years and females received higher doses and more prescriptions pre-PMP and experienced the greatest declines post-PMP.

Conclusions: Our study suggests that Iowa PMP implementation may have resulted in declines in OPR prescribing, and this impact varies by patient age and sex.