Analysis of prevalent and incident cases
Prevalent cases utilized members who contributed at least six months of benefits with the health plans to examine existing and new onsets of AF cases(6). The analysis of incident cases utilized members with at least 30 months of benefits with the health plans (suppl fig S1). This period ensured at least six months of benefits similar to members in the prevalence study together with allowing a period of 24 months without filing any medical and pharmacy claims. Piccini et al(2) used a similar methodology for the analysis of incident cases in administrative databases.
For inclusion, prevalent or incident cases had to contribute two or more medical claims and/or two or more medication claims as detailed in suppl fig S1. Prevalence was calculated over the period of the study with the denominator equal to the population count at the beginning of the study and the numerator to the unique persons filing claims during the analysis period as specified previously. An incidence rate was computed for new cases, with the denominator equal to the sum of person-years contributed by those in the incidence study with at least 30 or more months of benefits. The count and rates of prevalent and incident cases were computed for individual medical criteria (ER, hospital admission, office visit, office observation, or outpatient procedure), combined medical (ER, hospital admission, office visit, office observation, or outpatient procedures), all claims with AF ICD 10 codes, pharmacy criteria (anticoagulant or rhythm control medications), and combined medical/pharmacy.
The comorbidity profiles for prevalent and incident AF targets were analyzed for congestive heart failure, hypertension, diabetes mellitus, ischemic stroke, transient ischemic attack, thrombo-embolic events, myocardial infarction, peripheral artery disease, valvular disease, coronary artery disease, obstructive sleep apnea, and chronic kidney disease. The details of diagnosis codes for the comorbidity profiles are given in suppl table S3. We also determined the prevalence and incidence of multimorbidity (defined as ≥2 chronic long-term conditions – but for the purposes of this study, we also looked at AF with ≥2 chronic long term conditions).