Table E1.

Sensitivity analyses

Sensitivity analysis	Justification
1. Analyses for specific fracture outcomes were repeated, excluding subjects with a history of any prior fracture.	The main analysis approach, in which we only excluded those with a previous history of the specific fracture outcome under investigation, assumes that a fracture will only affect subsequent fracture probability in the same bone. However, a fracture in one bone can affect fracture risk in another bone. To test this, we repeated the main analysis after additionally excluding those with a history of any previous fracture.
2. Main analysis was repeated and restricted to those who registered with a general practice after 2006 and was additionally adjusted for ethnicity.	Ethnicity can affect fracture risk, but ethnicity was not routinely and accurately coded in the CPRD until 2006 onward, when its recording was incentivized in the quality and outcomes framework.
3. Main analysis was repeated on a redefined cohort in which the unexposed pool of individuals included those with a diagnosis of atopic eczema but without 2 records of treatment (did not fully meet the diagnostic criteria in the algorithm), and subjects remained in the unexposed pool until they fully met the criteria of the algorithm. This cohort was matched separately to the main analysis cohort.	To explore the sensitivity of the results to the definition of the exposure
4. Main analysis was repeated on a redefined cohort in which the exposed cohort included all individuals with an atopic eczema diagnostic code (did not require treatment codes). This cohort was matched separately to the main analysis cohort.	To explore the sensitivity of the results to the definition of the exposure
5. Main analysis was repeated after restricting to those with newly active atopic eczema (ie, first eczema diagnosis recorded during valid follow-up) and their matched counterparts.	To ensure that covariates measured at entry precede atopic eczema onset and are therefore less likely to lie on the causal pathway between atopic eczema and fracture outcomes
6. Main analysis was repeated, restricting the cohort to those who had visited their general practice in the year before entering the cohort.	To exclude practice nonattenders
7. Proximal humeral fracture analysis was repeated by using a stricter definition of proximal humeral fractures (excluding fractures coded as shoulder or upper arm fractures).	To assess the effect of proximal humeral fracture outcome definition in primary care given that there is no previously validated electronic health record based definition for proximal humeral fractures

Note: For simplicity, the any fracture outcome was used for all sensitivity analyses, except those testing the definition of specific fracture outcomes.