The usage of over-the-counter products by private insured patients in Germany - a claims data analysis with focus on complementary medicine.

Background: An important contribution to well-being of human beings can be observed by the use of self-medication products that is reflected in the constantly growing volume of over-the-counter (OTC) drugs. The aim of the current study was to extend the measurement concept for OTCs by exploring the relevance of the peripheral assortment provided by the widely accepted framework of the Anatomical Therapeutical and Chemical (ATC) classification of the WHO.

Methods: The focus was on the prescriptions and drug-related receipts submitted by privately insured persons to 18 private health insurers (PHIs) in Germany from the year 2016. The age- and gender-specific average claims amount per risks of outpatient drug expenditure were used as weights to scale up the relative distributions of the item amounts. The ATC-classification defines the commodity groups and discriminates between the main and the peripheral assortment. A descriptive analysis assessed the OTC frequencies and sum scores of the product groups within the main and peripheral assortment whereby the study group explored and assessed the relevance of each category independently according to the OTCs and integrative medicines.

Results: The analysis included 22.1 Mio. packages from the main assortment and examined 10.1 Mio. packages from the peripheral assortment. The latter was examined thoroughly and the commodity groups "Pharmaceutical food products", "Medicinal products for special therapy options" and particular "Hygiene and body care products" meet the defined requirements for OTCs relevant for integrative medicines. A high proportion of OTC products from the peripheral assortment was associated with the categories "medicinal products for special therapy options". Homeopathy and anthroposophy present two special therapy options, which are relevant for the extended OTC measurement.

Conclusions: The analysis of OTC drugs is feasible when the main and the peripheral assortment is available and enable to integrate about 18% of all OTCs, which are neglected by the common ATC-based approach. The presented extended approach may help to identify potential users of OTCs or people in need of OTC use. In case of the highly disputed homeopathy and anthroposophy products, more research among interactions with prescriptions drugs (Rx), nutrition's and other potentially harmful exposures is recommended.