Long-term incense use and the risk of end-stage renal disease among Chinese in Singapore: the Singapore Chinese health study

Table 2 Hazard ratios (95% CI) for risk of ESRD according to incense use (n = 63,147)

Exposure	Participants (n)/Person-years	ESRD
Exposure	Participants (n)/Person-years	Cases	Model 1	Model 2	Model 3
Status of incense use
Never users	6365/114,369	95	1.00 (reference)	1.00 (reference)	1.00 (reference)
Former users	8237/144,437	124	1.10 (0.84–1.44)	1.11 (0.84–1.45)	1.05 (0.80–1.38)
Current users	48,545/845,858	998	1.34 (1.08–1.66)	1.32 (1.07–1.64)	1.26 (1.02–1.57)
Non-users (never and former users)	14,602/248,167	219	1.00 (reference)	1.00 (reference)	1.00 (reference)
Current users	48,545/812,982	998	1.27 (1.09–1.48)	1.25 (1.08–1.46)	1.23 (1.05–1.43)
Frequency and duration of incense use
Non-users (never and former users)	14,602/258,806	219	1.00 (reference)	1.00 (reference)	1.00 (reference)
Current, less than daily users	3570/62,603	67	1.12 (0.85–1.48)	1.09 (0.83–1.44)	1.06 (0.81–1.40)
Current, daily users for ≤20 years	1310/24,268	17	0.93 (0.57–1.52)	0.95 (0.58–1.55)	0.98 (0.60–1.61)
Current, daily users for 21–40 years	5857/108,441	123	1.33 (1.06–1.67)	1.35 (1.07–1.70)	1.33 (1.06–1.67)
Current, daily users for > 40 years	37,808/650,547	791	1.29 (1.10–1.51)	1.27 (1.08–1.48)	1.24 (1.06–1.45)
P for trend			0.001	0.002	0.004

Model 1: adjusted for age at recruitment (years), gender, dialect (Cantonese, Hokkien), education level (no formal education, primary school, ≥ secondary school) and year of interview (1993–1995, 1996–1998)
Model 2: model 1 plus body mass index (kg/m²), physical activity (any weekly moderate activity, vigorous activity or strenuous sports lasting at least 30 min: yes or no), smoking status (never, former, current smokers), alcohol use (none, monthly, weekly, daily), total energy intake (kcal/day), total protein intake (gram/day, quartiles), red meat consumption (gram/day, quartiles), coffee consumption (None to < 1 cup/day, 1 cup/day, ≥ 2 cups/day), weekly ginseng intake (yes or no) and weekly medicinal soup intake (yes or no)
Model 3: model 2 plus self-reported history of physician-diagnosed hypertension, diabetes, coronary heart disease and stroke (yes or no)

ISSN: 1471-2369