Quantification of missing prescriptions in commercial claims databases: results of a cohort study

Abstract

PurposeThis study aims to quantify the magnitude of missed dispensings in commercial claims databases.MethodsA retrospective cohort study has been used linking PharMetrics, a commercial claims database, to a prescription database (LRx) that captures pharmacy dispensings independently of payment method, including cash transactions. We included adults with dispensings for opioids, diuretics, antiplatelet medications, or anticoagulants. To determine the degree of capture of dispensings, we calculated the number of subjects with the following: (1) same number of dispensings in both databases; (2) at least one dispensing, but not all dispensings, missed in PharMetrics; and (3) all dispensings missing in PharMetrics. Similar analyses were conducted using dispensings as the unit of analysis. To assess whether a dispensing in LRx was in PharMetrics, the dispensing in PharMetrics had to be for the same medication class and within ±7 days in LRx.ResultsA total of 1 426 498 subjects were included. Overall, 68% of subjects had the same number of dispensings in both databases. In 13% of subjects, PharMetrics identified ≥1 dispensing but also missed ≥1 dispensing. In 19% of the subjects, PharMetrics missed all the dispensings. Taking dispensings as the unit of analysis, 25% of the dispensings present in LRx were not captured in PharMetrics. These patterns were similar across all four classes of medications. Of the dispensings missing in PharMetrics, 48% involved a subject who had >1 health insurance plan.ConclusionsCommercial claims databases provide an incomplete picture of all prescriptions dispensed to patients. The lack of capture goes beyond cash transactions and potentially introduces substantial misclassification bias. © 2017 The Authors. Pharmacoepidemiology & Drug Safety Published by John Wiley & Sons Ltd.

To what extent do data from pharmaceutical claims under‐estimate opioid analgesic utilisation in Australia?

“…The issue of under‐ascertainment is a known limitation cited by researchers in many countries that use prescription registers and commercial claims databases to undertake pharmacoepidemiological studies . Given that pharmaceutical claims data primarily record dispensings of subsidised or insured prescription medicines, sales of unsubsidised and OTC opioids represent an important gap in data on opioid utilisation.…”

“…Table 1 compares the total utilisation in Australia of each opioid and overall, across the 2 data sources for the 2010 to 2014 calendar years, and Figure 1 The issue of under-ascertainment is a known limitation cited by researchers in many countries that use prescription registers and commercial claims databases to undertake pharmacoepidemiological studies. 4,5 Given that pharmaceutical claims data primarily record dispensings of subsidised or insured prescription medicines, sales of Despite the use of complete and population-level data sources being a key strength of this study, there are some limitations to consider when interpreting the findings. In particular, it is important to acknowledge that dispensed quantities, or the number of packs sold, do not directly equate to the amount used at the individual level, and there may be some deviations from the totals presented if accounting for differences between potential and actual use.…”

“…Historically, data on the utilisation of opioids and other medicines in Australia and internationally have been based largely on databases of pharmaceutical claims. These databases are readily accessible in many countries and generally provide comprehensive data on dispensings of reimbursed or subsidised prescriptions in community and outpatient settings . However, these data are also prone to under‐estimating medicines use.…”

“…These databases are readily accessible in many countries and generally provide comprehensive data on dispensings of reimbursed or subsidised prescriptions in community and outpatient settings. 4,5 However, these data are also prone to underestimating medicines use. Estimates based on pharmaceutical claims alone are especially problematic for studies of opioids in countries such as Australia where formulations and items below a reimbursement (or co-payment) threshold are not recorded, 6 and where some opioids are available for purchase over-the-counter (OTC).…”

Comparative risk of serious hypoglycemia with oral antidiabetic monotherapy: A retrospective cohort study

“…The rationale for this exclusion was to avoid areas of nonoverlap in the propensity score (PS), since pregnant women treated with an SU receive glyburide almost exclusively . As claims‐based approaches to identifying new users are imperfect, we recognized that a small proportion of subjects might actually be prevalent antidiabetic drug users. Persons could enter the cohort more than once if they re‐met inclusion criteria after a censoring event (described below).…”