Previous Surgical Exposure and the Onset of Degenerative Cervical Myelopathy: A Propensity-Matched Case-Control Analysis Nested Within the UK Biobank Cohort

Study design: Case-control study.

Objectives: Degenerative Cervical Myelopathy (DCM) is a progressive neurological condition caused by mechanical stress on the cervical spine. Surgical exposure in the preceding months to a DCM diagnosis is a common theme of Patient and Public Involvement (PPI) discussions. Such a relationship has biological plausibility (e.g. neck positioning, cord perfusion) but evidence to support this association is lacking.

Methods: We analysed UK Hospital Episode Statistics (HES) data for participants in the UK BioBank cohort. We defined cases as those episodes with a primary diagnosis of DCM and generated controls using non-DCM HES episodes. Cases and controls were propensity score-matched by age, sex and date of episode, and a directed acyclic graph was used to robustly control for confounders. We defined the exposure as any surgical procedure under general or regional anaesthetic occurring within the 6-24 months prior to the episode.

Results: We analysed 806 DCM and 2287432 non-DCM hospital episodes. On multivariable logistic regression analysis, the odds ratio (95% CI) for the effect of a binarised (0 vs ≥ 1) exposure on risk of developing DCM was 1.20 (1.02-1.41), and for categorised (0 vs 1 and 0 vs ≥ 2) exposure was 1.11 (0.882-1.39) & 1.33 (1.075-1.65).

Conclusions: This study supports the patient narrative of surgery as a risk factor for the development of DCM. The association displays temporality, dose-response relationship, and biological plausibility. Further work is needed to confirm this in other cohorts, explore mediating mechanisms, and identify those at greatest risk.