Background: The prevalence of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) in the US is largely unknown. Prior research has estimated PAH prevalence in Europe at ∼15-52 per million.

Methods: Using a privately insured claims database (1999-2007) for the under age 65 population and a Medicare claims database for the 65+ population, and following the current clinical classification of PH, CTEPH patients were identified as having: ≥2 claims for pulmonary hypertension (PH) [ICD-9-CM: 416.0, 416.8]; ≥1 claim for pulmonary embolism (PE) ≤12 months prior or 1 month after the initial PH claim (index date). PAH patients were identified: ≥2 claims for primary PH [416.0]; no left heart disease, lung diseases, CTEPH, or miscellaneous PH diagnoses ≤12 months prior or 1 month after the index date. Both cohorts were required to have ≥1 claim for right heart catheterization ≤6 months prior to any PH claim, or ≥1 claim for echocardiogram ≤6 months prior to a specialist-diagnosed PH claim. Age- and gender-standardized prevalence rates per million individuals (PMI) were calculated using appropriate population weights.

Results: Prevalence rates (95% CI) of CTEPH were estimated at 63 (34-91) PMI among the privately insured (<65), and 1007 (904-1111) PMI among the Medicare population (≥65). The corresponding estimates for PAH were 109 (71-146) PMI among the <65 population, and 451 (384-519) PMI for Medicare.

Limitations: Identification of PAH and CTEPH patients in administrative claims data is challenging, due to lack of specific ICD-9-CM codes for the conditions and risk of misdiagnosis.

Conclusions: Prevalence rates of CTEPH and PAH increase with age, and are higher among women. The increased risk of PE may explain the sharp age gradient for CTEPH prevalence. The estimated US prevalence of PAH is higher than existing estimates.