Survival protection by bodyweight in isolated scleroderma-related pulmonary artery hypertension

In chronic heart failure (CHF) due to systemic cardiovascular disease, obese patients have better survival. Bodyweight versus survival was analyzed post hoc in subjects with limited scleroderma (SSc) and isolated pulmonary artery hypertension (PAH), i.e. with CHF due to pulmonary vascular disease. Rheumatologists referred scleroderma subjects for evaluation, and PAH was ascertained by right heart catheterization (RHC). Forty-nine SSc-PAH subjects were stratified by body mass index (BMI): obese 7 (14.3 %), overweight 11 (22.4 %), normal weight 21 (42.9 %), and underweight 10 (20.4 %) for 24-month follow-up and pooled together for long-term 72-month follow-up. Survival was analyzed by Kaplan-Meier method. Multivariate Cox proportional hazards modeling helped to assess variables associated to survival. At 24 months (17 events), survival increases with BMI across four groups (logrank for trend P = 0.031). By Cox multivariate mortality, best model included: BMI (P = 0.043), low lung diffusion (DLco, P = 0.007), and reduced stroke volume index (SVI, P = 0.017). At 72 month (37 events), higher BMI values were associated with better survival but not significantly (P = 0.076). By multivariate modeling BMI did not enter any model, whereas low DLco entered all (P < 0.001). Also low SVI (P = 0.02) and low mixed venous saturation (SvO2, P = 0.009) were associated with the prognosis. From PAH diagnosis to final event, BMI had small (5.4 %), but significant decline (P < 0.001). This is ascribed to CHF progression, and may explain BMI predictive power weakening. The results suggest BMI decline should be contrasted, DLco is useful for screening and with SVI and SvO2 for assessing prognosis and treatment.