Table II.
ORs for risk of RCC in relation to mtDNA copy number, overall and stratified by time from blood collection to case diagnosisa
| mtDNA copy numberb | Overall | <6 years to RCC diagnosis | ≥6 years to RCC diagnosis | |||
|---|---|---|---|---|---|---|
| Ca/Co | OR (95% CI) | Ca/Co | OR (95% CI) | Ca/Co | OR (95% CI) | |
| First quartile | 42/116 | 1.0 (Ref) | 22/116 | 1.0 (Ref) | 20/116 | 1.0 (Ref) |
| Second quartile | 47/118 | 1.0 (0.6–1.7) | 16/118 | 0.6 (0.3–1.3) | 31/118 | 1.5 (0.8–2.9) |
| Third quartile | 64/117 | 1.5 (0.9–2.5) | 30/117 | 1.3 (0.7–2.4) | 34/117 | 1.7 (0.9–3.3) |
| Fourth quartile | 77/117 | 2.0 (1.2–3.2) | 37/117 | 1.4 (0.8–2.7) | 40/117 | 2.6 (1.4–5.0) |
| P trend = 0.002 | P trend = 0.078 | P trend = 0.003 | ||||
Ca, case; Co, control.
aAnalyses were performed using unconditional models adjusted for matching factors (age, sex, race, year of blood draw, season of blood draw, study year and material type for DNA extraction) as well as history of hypertension, smoking status and BMI. Tests for trend were performed by assigning the within-category median for each quartile and analyzing these data as a continuous variable. Analyses stratified by time from blood collection to RCC diagnosis were performed using polytomous logistic regression models.
bQuartiles of mtDNA copy number were assigned based on the distribution among controls as follows: first quartile, ≤95; second quartile, 96–120; third quartile, 121–150; fourth quartile, ≥151.