PPD data model

MDR, dm+d, and CDR

The MDR is the legacy database on which dispenser payments is based. It most notably is mapped to BNF code only, which makes it hard to make use of the rich metadata available in the publicly-available dm+d NHS database. It also has a restriction of 40 characters on the BNF Name field.

dm+d is itself generated from CDR, which is the next-generation payments database that's been in development for around a decade.

CDR notes

BNF Code mappings

We can map from PPD data (which is supplied in MDR format) to dm+d via a mapping which is updated by NHSBSA every quarter. As dm+d is updated monthly, this means it's possible for some actively prescribed dm+d products to have no corresponding BNF Code mapped; however, given the lag of 8+ weeks between a dispensing event and the release of the monthly PPD data, this is unlikely ever to be a problem.

MDR field notes

What is quantity?

• Broken bulk: not reflected in quantity number

What is actual_cost?

• Doesn't reflect broken bulk, or other costs based on prescribing which cannot be directly attributed to practices. These costs include VAT, nationally unidentified prescribing, broken bulk, schedule adjustments, net cross boundary costs and out of pocket expenses and payments for containers for national unidentified prescribing (source)