Increased Risk of Ischemic Heart Disease in Patients With Systemic Lupus Erythematosus

Taiwanese patients with systemic lupus erythematosus (SLE) were at a higher risk of developing ischemia heart disease (IHD), particularly between the 6th and 9th year post-SLE diagnosis, according to a study published in BMC Rheumatology.¹ Investigators believe advanced cardiac health examinations, as well as a health education plan, should be recommended for this patient population prior to the 6th year after SLE diagnosis.

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IHD, a major cause of mortality worldwide, is a serious disease with a high likelihood of sudden death. In 2020, 20,457 patients died of IHD, more than half of which were men (n = 11,809), who were frequently the primary breadwinners.²

“Even though healthcare quality has improved for SLE and IHD in the last century, SLE progression to IHD is still unavoidable,” wrote a group of Taiwanese investigators. “The major difference between today and the previous century is air pollution.”

A retrospective cohort study utilized data from Taiwan’s National Health Insurance Research Database (NHIRD) and Taiwan Air Quality Monitoring. Outpatient data, admission, pharmaceutical information, physical examination, and medical records were collected from the NHIRD.

The primary endpoints were to determine the hazard ratio (HR) of IHD after SLE diagnosis and to evaluate the effects of air pollution exposure on IHD in SLE for 12 years.

Adult patients (aged ≥20 years) who were diagnosed with SLE in 2006 without IHD were used as the SLE group. Investigators then randomly selected a sex-matched, non-SLE cohort, 4 times larger than the SLE cohort, as controls. Air pollution indices by residence city per period were used to calculate the exposure.

Life-table method analysis with log-rank tests evaluated the differences in SLE between male and female patients, while Cox proportional hazard regression analyses were used to examine the HR of IHD in both SLE and control groups.

A total of 4842 patients (male n = 1644, female n = 3198) were placed in the SLE group and 19,368 (male n = 5,624, female n = 13,744) were identified as controls.

At the end of 2018, the risk of IHD was significantly higher in the SLE cohort when compared with controls, with risks peaking between the 6th and 9th year post-diagnosis. IHD incidence rate during the follow-up period was 9.2% and 4.8% for men and women in the SLE cohort, respectively, compared with 2.3% and 3.5%, respectively, in the control cohort.

The HR of incidence of IHD for patients with SLE was 2.42 times higher compared with controls. The risk of developing IHD in both groups was significantly correlated with male sex (SLE group: HR = 1.817, P <.01; control group: HR = 1.609, P <.01), age, and PM10 exposure (SLE group: HR = 66.197, P <.01; control group: HR = 108.945, P <.01).

The log-rank test demonstrated a statistically significant difference in IHD incidence between the SLE and control cohorts (P <.001).

Investigators noted using the health insurance database may have limited results as patients were only recruited using the International Statistical Classification of Diseases and Related Health Problems (ICD-9) code. The database did not include information on smoking and drinking status, family history, medication adherence, and psychosocial data, including depression and anxiety diagnoses.

Additionally, residence status may have been partly inaccurate as patients may have moved during the follow-up period. Lastly, both direct and second-hand smokers are at risk of nicotine exposure, one of the risk factors for atherosclerosis. Investigators urge future studies to evaluate whether carbon monoxide in exhaled breath can be used in non-smokers to determine smoking status.

“Case managers should make sure that education on diet and exercise is included in the health education plan for first-diagnosed SLE patients,” investigators concluded. “The health education plan could promote a healthier lifestyle for SLE patients to reduce the risk of atherosclerosis or IHD.”

References

1. ^{Chen PY, Tsan YT, Yang CT, et al. Prediction of risk of ischemic heart disease in first-diagnosed systemic lupus erythematosus patients in taiwan: is air pollution exposure a risk factor?. BMC Rheumatol. 2023;7(1):14. Published 2023 Jun 8. doi:10.1186/s41927-023-00337-8}
2. ^{Ministry of Health and Welfare., M. Statistics on the causes of death of Taiwan in 2020. 2021.}