By Lynda Williams, Senior medwireNews Reporter
Japanese patients respond well to pulmonary arterial hypertension (PAH)-targeted drugs and may have a good prognosis with long-term survival, study findings suggest.
The review of 56 Japanese patients with idiopathic/heritable PAH, diagnosed at an average age of 32 years, showed that 96% of patients survived for 5 years after diagnosis, with 78% surviving for 10 years.
The mean survival from diagnosis was 14.9 years, with six patients dying from heart failure and one from alveolar haemorrhage, report Hiromi Matsubara (National Hospital Organization Okayama Medical Center, Japan) and co-authors.
The majority (93%) of patients were treated with prostacyclin analogues, endothelial antagonists (68%) and/or phosphodiesterase type 5 inhibitors (52%), with patients also given warfarin (23%) and oxygen (95%). One patient responded to a calcium channel blocker.
Treatment significantly improved haemodynamic parameters. After 3.7 years of follow-up, patients achieved an average 28-mmHg decrease in mean pulmonary arterial pressure (mPAP), from 63 to 35 mmHg, and a cardiac index rise from 2.3 to 3.5 L/min per m2.
This was accompanied by a significant improvement in World Health Organization (WHO) functional class from III to II and a reduction in right atrial pressure (RAP) from 8 to 5 mmHg. In addition, brain natriuretic peptide (BNP) improved from 313 to 67 pg/mL and the 6-minute walk distance increased from 234 to 378 m.
Analysis of baseline variables revealed that survival was not predicted by age, gender, hereditary status, or PAH-targeted treatment, but patients with a baseline BNP level of 350 pg/mL or above had a significantly poorer prognosis than patients with a lower value. And patients with a SpO2 of 96% or less at baseline had significantly worse survival than those with a SpO2 above this threshold.
With regard to follow-up variables, although WHO class I and II status, 6-minute walk distance, BNP, mPAP, RAP and cardiac index were significant predictors of survival in initial analysis, none of these remained significant in multivariate analysis.
Writing in Life Sciences, the researchers say that overall survival was higher than previously reported for Western patients. While this may be due to the high use of PAH-targeted therapy in the cohort, Matsubara et al note that prognosis was also better than expected in a study of Chinese patients, who are likely to choose inexpensive drugs or discontinue treatment.
“There might be a difference in the genetic background between Asians and Caucasians that leads to a different response to treatment,” the authors comment.
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