Leading Causes of Death Differ by PH Type, Study Shows

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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The leading causes of death among people with pulmonary hypertension (PH) differ by PH type, a Japanese study has found.

When categorized using the World Health Organization (WHO) PH classification, those in group 1 died mostly from PH itself, those in group 3 died more often from respiratory failure due to underlying lung disease, and those in group 4 died most frequently from malignancies like cancer, the data showed.

“With expectations of further treatment progress and longer survival, more research on the PH-type specific cause of death is anticipated, which will foster optimal follow-up and improve outcomes in each PH patient group,” the researchers wrote.

The study,”Various factors contribute to death in patients with different types of pulmonary hypertension: A retrospective pilot study from a single tertiary center,” was published in the journal Respiratory Investigation

The WHO PH classification divides PH patients into five groups according to their underlying cause of disease. While much is known about the differences between these PH types, more information is needed to better understand how their survival rates and causes of death differ in order to achieve better patient care.

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A research team in Japan analyzed the causes of death among 80 PH patients seen at their clinic from 2001 to 2020. Patients included in the analyses were from WHO group 1 (pulmonary arterial hypertension, or PAH); group 3 (PH due to lung disease); or group 4 (PH due to blood clots).

Among 312 patients seen at their clinic, 98 died. Of those, 80 met the inclusion criteria and their cause of death was analyzed.

Among these 80 patients, 28 were in group 1, 39 in group 3, and 13 in group 4. The median age of those in group 1 at diagnosis was 59.3, group 3 was 69.2,   and group 4 was 65.8.

Overall, the causes of death were different among the three groups.

The leading cause of death in group 1 was PH (61%), which was higher than in groups 3 (21%) or 4 (23%). Causes of death not due to PH in group 1 included liver disease, respiratory failure, infection, or bleeding.

Patients in group 1 who died of PH also showed increases in levels of brain natriuretic peptide (BNP), a biomarker of heart dysfunction, more commonly than those who died of other causes, “indicating that monitoring BNP may predict the cause of death and thus, help to guide optimal patient management,” the researchers wrote.

In group 3, PH-related deaths were the most prevalent (56%), and most patients (71%) died of respiratory failure, consistent with the fact that group 3 encompasses patients with PH due to lung disease. In contrast, 36% of group 1 deaths and 30% of group 4 deaths were due to respiratory failure. Those in group 3 who died of lung failure had lower BNP levels.

In group 3, those who also had systemic sclerosis, a connective tissue disease, died due to PH more frequently than those who had not.

PH-related and PH-unrelated deaths were equal among those in group 4 (38%). Malignant disease, such as cancer, was a more predominant cause of death in this group (60%) than in the other two groups (0% of group 1 and 13% of group 3).

“This finding emphasizes the importance of continuous workups for the possibility of malignant disease during follow-up, as well as at the time of diagnosis in group 4 PH patients,” the researchers wrote.

Overall, the findings highlight that factors contributing to death in PH patients varies significantly by WHO group.

Given the small number of patients from one center, the researchers noted they “consider the present investigation as a pilot study,” adding that the findings “cannot be directly extrapolated to different PH patient cohorts.”

“Recognizing the exact cause of death is critically important to improve the survival outcome in patients with PH. Our results stress the need for detailed evaluation on the cause of death in future studies and registries on PH,” the team wrote.

They noted that future studies should include an analysis of the potential impacts of PH therapies on causes of death in patients.