BackgroundFew controlled clinical trials exist to support oral combination therapy in pulmonary arterial hypertension (PAH).MethodsPatients with PAH (idiopathic [IPAH] or associated with connective tissue disease [APAH-CTD]) taking bosentan (62.5 or 125 mg twice daily at a stable dose for ≥3 months) were randomized (1:1) to sildenafil (20 mg, 3 times daily; n = 50) or placebo (n = 53). The primary endpoint was change from baseline in 6-min walk distance (6MWD) at week 12, assessed using analysis of covariance. Patients could continue in a 52-week extension study. An analysis of covariance main-effects model was used, which included categorical terms for treatment, baseline 6MWD (<325 m; ≥325 m), and baseline aetiology; sensitivity analyses were subsequently performed.ResultsIn sildenafil versus placebo arms, week-12 6MWD increases were similar (least squares mean difference [sildenafil–placebo], −2.4 m [90% CI: –21.8 to 17.1 m]; P = 0.6); mean ± SD changes from baseline were 26.4 ± 45.7 versus 11.8 ± 57.4 m, respectively, in IPAH (65% of population) and −18.3 ± 82.0 versus 17.5 ± 59.1 m in APAH-CTD (35% of population). One-year survival was 96%; patients maintained modest 6MWD improvements. Changes in WHO functional class and Borg dyspnoea score and incidence of clinical worsening did not differ. Headache, diarrhoea, and flushing were more common with sildenafil.ConclusionsSildenafil, in addition to stable (≥3 months) bosentan therapy, had no benefit over placebo for 12-week change from baseline in 6MWD. The influence of PAH aetiology warrants future study.Trial registrationClinicalTrials.gov NCT00323297 (registration date: May 5, 2006).Electronic supplementary materialThe online version of this article (10.1186/s12872-017-0674-3) contains supplementary material, which is available to authorized users.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a complication of unresolved organised pulmonary emboli/thrombi obstructing the major pulmonary arteries. The aim of this study was to estimate the incidence and risk factors of CTEPH in a cohort with first venous thromboembolism (VTE). This was a population-based cohort study of patients with first VTE and no active cancer in England between 2001 and 2012. CTEPH was assessed using a rigorous case-ascertainment algorithm. Risk factors for CTEPH were studied using a nested case-control approach by matching CTEPH cases to VTE patients without CTEPH. Adjusted odds ratios (OR) of comorbidities were estimated from conditional logistic regression. During 81,413 person-years of follow-up among 23,329 patients with first VTE (mean follow-up 3.5 years; maximum 11.0 years) 283 patients were diagnosed with CTEPH (incidence rate 3.5 per 1000 person-years); cumulative incidence was 1.3% and 3.3% at 2 and 10 years after pulmonary embolism, and 0.3% and 1.3% following deep vein thrombosis (DVT), respectively. Risk factors for CTEPH included age over 70, OR 2.04 (95% CI 1.23 to 3.38), female gender, 1.44 (1.06 to 1.94), pulmonary embolism at first VTE, 3.11 (2.23 to 4.35), subsequent pulmonary embolism and DVT, 3.17 (2.02 to 4.96) and 2.46 (1.34 to 4.51) respectively, chronic obstructive pulmonary disease 3.17 (2.13 to 4.73), heart failure 2.52 (1.76 to 3.63) and atrial fibrillation, 2.42 (1.71 to 3.42). CTEPH develops most commonly after pulmonary embolism and less frequently after DVT. Awareness of risk factors may increase referrals to specialised centres for confirmation of CTEPH and initiation of specific treatment.

Despite exhibiting pulmonary hypertension-related symptoms, many pulmonary embolism patients did not undergo imaging tests that could diagnose pulmonary hypertension or chronic thromboembolic pulmonary hypertension. This study suggests that physician education about the risk of pulmonary hypertension and chronic thromboembolic pulmonary hypertension after pulmonary embolism may need to be improved.

BackgroundLittle is known concerning the degree to which initiation of sildenafil for pulmonary arterial hypertension (PAH) impacts patterns of healthcare utilization and costs.MethodsUsing a large US health insurance claims database, we identified all patients with evidence of PAH (ICD-9-CM diagnosis codes 416.0, 416.8) who received sildenafil between 1/1/2005 and 9/30/2008. Date of the first-noted prescription for sildenafil was designated the “index date,” and claims data were compiled for all study subjects for 6 months prior to their index date (“pretreatment”) and 6 months thereafter (“follow-up”); patients with incomplete data during either of these periods were excluded. Healthcare utilization and costs were then compared between pretreatment and follow-up for all study subjects.ResultsA total of 567 PAH patients were identified who began therapy with sildenafil and met all other study entry criteria. Mean (SD) age was 52 (10) years; 73% were women. Healthcare utilization was largely unchanged between pretreatment and follow-up, the only exceptions being decreases in the mean number of emergency department visits (from 0.7 to 0.5 per patient; p < 0.01) and the percentage of patients hospitalized (from 35% to 29%; p = 0.01). The mean cost of all PAH-related medication was $7139 during pretreatment and $14,095 during follow-up (sildenafil cost during follow-up = $5236); exclusive of PAH-related medications, however, total healthcare costs decreased modestly (from $30,104 to $27,605) (p < 0.01 for all comparisons).ConclusionsThe cost of sildenafil therapy may be partially offset by reductions in other healthcare costs.

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