Despite the frequent assertion that survival has improved in recent years for patients who have pulmonary hypertension associated with systemic sclerosis, a meta-analysis that allowed pooling of data from numerous small studies shows otherwise.
In a report published online Aug. 26 in Arthritis & Rheumatism, 3-year survival was only 52% in these patients. This confirms that pulmonary hypertension is a severe complication of, and a leading cause of death in, systemic sclerosis, said Dr. Guillame Lefèvre of Université Lille Nord de France in Lille, and his associates.
Many studies have examined survival in systemic sclerosis–associated pulmonary hypertension (PH) and have asserted that survival has improved of late, but none have clearly demonstrated such a trend because they haven’t fully accounted for confounding factors such as baseline differences in disease severity over time. Dr. Lefèvre and his colleagues assessed survival by pooling the data on 2,244 adult patients who participated in 22 cohort studies between 1960 and 2012 in which detailed information on prognostic factors was included.
Overall, 83% of the patients were women; 79% had limited cutaneous systemic sclerosis, and 18% had diffuse cutaneous disease. The mean patient age was 60 years, and 83% were white.
The pooled survival rates were 81% at 1 year, 64% at 2 years, and 52% at 3 years.
There was no evidence that survival has improved over time. In fact, the evidence indicated instead that because of screening programs and increased awareness of the disease in recent years, contemporary patients are being diagnosed sooner in the course of the disease, and thus have less severe disease at presentation than do their counterparts diagnosed 30 or 40 years ago, the investigators said (Arth. Rheum. 2013;65: 2412-23 [doi:10.1002/art.38029]).
This study could not assess whether newer treatments may have contributed to the impression that survival has improved over time, because of the extreme heterogeneity of therapies across the 22 studies and the numerous instances of missing data on this topic.
However, several factors other than time trends and therapies were found to correlate with improved survival.
Disease severity at baseline, as measured by hemodynamic factors (particularly pulmonary vascular resistance), was strongly correlated with survival. Beyond that, prognostic factors were found to be quite different between pulmonary arterial hypertension (PAH) and PH related to interstitial lung disease (ILD-associated PH).
Three-year survival was deemed "dismal" for ILD-associated PH at 35%, compared with the 56% 3-year-survival for PAH.
In PAH, older age at diagnosis, male gender, worse New York Heart Association functional class, shorter 6-minute walk distance, pericardial effusion, and adverse results on several laboratory tests (diffusing capacity for carbon monoxide, right atrial pressure, mean pulmonary artery pressure (mPAP), cardiac index, and pulmonary vascular resistance) all were significant prognostic factors. In contrast, subtype of systemic sclerosis, the presence or absence of anticentromere antibodies, forced vital capacity, and pulmonary capillary wedge pressure were not significant prognostic factors.
In ILD-associated PH, only pericardial effusion and diffusing capacity for carbon monoxide were found to be prognostic factors.
It was somewhat surprising that 6-minute walk distance proved to be a good predictor of survival in this study, because it has been considered by many researchers to be a poor prognostic tool. Several studies have reported that this test reflects many factors unrelated to pulmonary function, such as musculoskeletal impairment or depression. Yet 6-minute walk distance was clearly predictive in this metaanalysis, Dr. Lefèvre and his associates said.
Similarly, the pooling of data in this study showed that factors such as cardiac index, pulmonary vascular resistance, right atrial pressure, and mPAP were useful for prognosis. Previous studies that argued against the usefulness of these factors probably had sample sizes that were too small to demonstrate a significant association with survival, they added.
Dr. Lefèvre’s associates reported ties to Actelion, Bayer, GlaxoSmithKline, Novartis, Pfizer, and Lilly.