Incense Use and the Risk of Chronic Limb-Threatening Ischemia Among Middle-Aged and Older Adults in the Singapore Chinese Health Study

Background: Epidemiologic studies have shown that daily exposure to incense smoke is associated with greater risk of cardiovascular mortality, which suggests that chronic exposure to incense could be linked to atherosclerosis. We studied the association between home incense use and the risk of chronic limb-threatening ischemia (CLTI), the most severe outcome of peripheral arterial disease.

Methods: We used data from the Singapore Chinese Health Study, which recruited 63,257 Chinese participants 45-74 years old from 1993-1998. Data were collected via in-person interviews conducted at the participants' homes by trained interviewers. Linkage to the nationwide hospital discharge database was used to determine incident cases, defined as participants who underwent revascularization or lower extremity amputation for CLTI. Association between use of incense and risk of CLTI was examined using multivariable Cox proportional hazards regression models, adjusted for demographics and cardiovascular risk factors.

Results: In this cohort, 76.9% were current users of incense at recruitment, and 92.6% of those used incense daily at home. During a mean 18.8 years of follow-up, 1,097 participants developed CLTI. Compared to never or former users, current users had a 22% higher risk of CLTI [hazard ratio ; 95% confidence interval (CI): 1.04, 1.43]. The risk was greater with chronicity of use, and the HR was highest and statistically significant in participants who had used incense daily for years [ (95% CI: 1.06, 1.46)]. The results did not differ by sex, history of diabetes, or smoking status.

Conclusions: Daily exposure to incense in the home environment for more than 40 years was associated with a greater risk of developing CLTI. https://doi.org/10.1289/EHP14674.