Cochrane review of 93 studies links pharma payments and gifts to doctors with more and costlier prescribing

A systematic review published in the Cochrane Database of Systematic Reviews analysed 93 studies on how promotional contacts between pharmaceutical companies and prescribers relate to the appropriateness, quantity and cost of prescribed medicines. The authors searched CENTRAL, MEDLINE, Embase, one other database and two trial registers up to January 2025. Of the included studies, 82 (88%) were conducted in the USA and 11 in the European Union or the UK. doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

Included studies and methods

Sixty studies were cross-sectional, 23 were controlled cohort studies, four were controlled before-after studies, four were interrupted time series, one was a nested case-control study and one was a randomised trial. Sixty-two studies examined payments, gifts or other transfers of value. Sixteen examined advertising or education, mainly sales representative visits, seven examined free samples, and eight examined conflict-of-interest policies. doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

Because of heterogeneity, the authors could not run meta-analyses and summarised the results narratively, rating certainty with GRADE. The one randomised trial had a high risk of bias for both of its outcomes. In the cross-sectional and cohort studies, the main concern was the handling of confounding factors. doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

Associations with prescribing

Receipt of gifts and payments was associated with decreased prescribing appropriateness (10 studies; 2,941,948 prescribers) and a larger quantity of prescriptions (39 studies; 3,858,871 prescribers). It was probably associated with higher prescribing costs (25 studies; 2,505,292 prescribers). doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

Exposure to advertising or education may be associated with decreased appropriateness (6 studies; 1335 prescribers) and higher costs (2 studies; 986 prescribers). It is probably associated with a larger quantity of prescriptions (7 studies; 151,399 prescribers). Evidence on free samples is very uncertain. doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

Institutional conflict-of-interest policies were probably associated with improved appropriateness (2 studies; 3065 prescribers) and may be associated with fewer prescriptions (6 studies; 110,470 prescribers). Their effect on costs is uncertain. Only one study with 105 prescribers examined formulary requests, and its evidence is very uncertain. doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

The authors concluded that promotional interactions are probably associated with less appropriate prescribing, more medicines prescribed or provided, higher costs and a greater likelihood of recommending hospital formulary additions of the company's drugs. doi.orgCochrane Database of Systematic Reviewsdoi.orgOpen source ↗

Co-author Quinn Grundy of the University of Toronto said that in the USA, where payments are reported in a public database, just over half of all licensed physicians accepted a payment, including free meals.