Association between polycythemia and risk of ischemic stroke in males based on the national health insurance service-health screening cohort

ABSTRACT

Background

Polycythemia, a state in which the hematocrit or hemoglobin (Hb) concentration in the peripheral blood increases, is associated with several thrombosis-related diseases, of which cerebral infarction is relatively common. This study aimed to investigate the association between ischemic stroke and polycythemia, as a potential risk factor.

Research design and methods

This study included men who had undergone national health checkups between 2002 and 2003; the data were extracted from the Korean National Health Insurance Service-Health Screening database. The primary outcome was the risk ischemic stroke; adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for ischemic stroke were calculated using Cox proportional hazards regression models.

Results

In total, 207,737 male participants aged 40–79 years were included in this study. At the baseline, 13972 (6.7%) participants met the polycythemia criteria (Hb >16.5 g/dL). During the study period, 897 and 12,440 cases of ischemic stroke occurred in the polycythemia and normocythemia (13.0 g/dL ≤ Hb ≤16.5 g/dL) groups, respectively. Compared with the normocythemia group, the polycythemia group showed an adjusted HR (95% CI) for ischemic stroke of 1.12 (1.04–1.20).

Conclusions

The risk of ischemic stroke was higher in participants with polycythemia than in those with normocythemia.

KEYWORDS:

• hemoglobin
• polycythemia
• ischemic stroke
• stroke
• Cerebrovascular disorders
• Infarction
• Thrombosis

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Author contributions

Hyo-Sun You and Sang-Jun Shin contributed equally to this study as coauthors, and Hee-Taik Kang and Joungyoun Kim supervised the entire study as co-corresponding authors. Hyo-Sun You and Hee-Taik Kang made the conception and design of this study. Sang-Jun Shin and Joungyoun Kim conducted statistical analysis and interpretation of the data. Hyo-Sun You and Sang-Jun Shin drafted of the paper, all authors were involved in revising paper for intellectual content. All authors agree to be accountable for all aspects of the work, and approved the publication of the final version.

Data sharing and data accessibility

We used data from the Korean National Health Insurance Service (NHISS) data-sharing service. The NHISS data are accessible only to authorized users. To access the data, when users complete an application for research purposes, NHISS, the data provider, reviews it and permits access to the database. The data were available only within the application period and accessible using a remote research and analysis system through a server operated by the NHISS. In addition, the data were anonymized to protect personal information. Because it operates based on such a system, anyone can apply for data for research purposes; however, only researchers who have been approved can access the data.

Additional information

Funding

This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (grant no.,2021R1G1A1006485