Context

The original codelists are available in the Appendix S1, and their curation is described in the methods section of the main manuscript. Construction of these codelists into clinical variables underlying the Cambridge Multimorbidity Score is described in the Appendix S2, Table S3.1.

Methods

The original codelists were constructed in DMD and have become outdated. New codelists were created as follows:

1) First, the outdated DMD terms from the original codelists were filtered out by comparison to the current DMD dictionary. 2) Then, they were mapped back to BNF codes using NHSBSA mapping July 2026: https://www.nhsbsa.nhs.uk/prescription-data/understanding-our-data/bnf-snomed-mapping; matching on the DMD code only. 3) Resulting pseudo BNF codelists were re-uploaded to Opencodelists. We identified the highest-level common parent codes and manually reviewed all child codes of those parents for inclusion. 4) Parent codes most often corresponded to BNF chapters, but to ensure completion, relevant BNF chapters were searched manually. 5) Some medication terms which appeared in the original Tsang codelists were removed, as they were irrelevant to the defined condition (e.g. topical lithium creams were excluded from the bipolar codelist). For this reason, the current codelists are manually curated to define diseases for the Cambridge Multimorbidity Score, rather than a copy of the Tsang Codelists. 6) Details of decisions on any borderline cases are recorded in the Github link.

Bordeline cases

The IBS prescription (antispasmodic) codelist is intended to include only antispasmodic medications used in the treatment of IBS, as intended in Tsang et al. Other medications commonly used in IBS (e.g. simeticone or laxatives) are not included. Similarly, bowel motility medications not typically used in IBS (e.g. glycopyrronium bromide used in palliative care or cisapride for paresis) are not included.

Additional information

An earlier, unpublished version of this pseudo BNF codelist also received clinical input from Prof. Michael Marks, LSHTM.