Association of red cell distribution width with all-cause and cardiovascular-specific mortality in African American and white adults: a prospective cohort study

Table 3 Stratified analysis of the association between red cell distribution width and all-cause mortality

RDW^a	HR^b (95% CI)	HR^b (95% CI)	P-interaction^c
Sex	Men	Women
RDW-Q1	1.00	1.00	0.42
RDW-Q2	1.39 (0.73–2.67)	0.71 (0.34–1.47)
RDW-Q3	1.20 (0.60–2.38)	0.85 (0.42–1.7)
RDW-Q4	2.41 (1.26–4.59)	1.17 (0.6–2.28)
P-trend^d	0.006	0.29
Race	African Americans	Whites
RDW-Q1	1.00	1.00	0.35
RDW-Q2	0.76 (0.4–1.44)	1.68 (0.79–3.59)
RDW-Q3	0.86 (0.46–1.58)	1.57 (0.71–3.49)
RDW-Q4	1.18 (0.66–2.1)	3.60 (1.68–7.72)
P-trend^d	0.22	0.001
Poverty status	Above	Below
RDW-Q1	1.00	1.00	0.17
RDW-Q2	1.62 (0.76–3.49)	0.85 (0.45–1.61)
RDW-Q3	2.17 (1.03–4.56)	0.63 (0.32–1.24)
RDW-Q4	2.80 (1.33–5.92)	1.33 (0.74–2.4)
P-trend^d	0.005	0.18
Current smoking	No	Yes
RDW-Q1	1.00	1.00	0.42
RDW-Q2	1.31 (0.61–2.81)	1.04 (0.56–1.94)
RDW-Q3	0.82 (0.34–1.99)	1.28 (0.71–2.31)
RDW-Q4	1.83 (0.82–4.06)	1.82 (1.03–3.23)
P-trend^d	0.17	0.01
BMI	BMI < 25.0	BMI ≥ 25.0
RDW-Q1	1.00	1.00	0.004
RDW-Q2	1.16 (0.59–2.28)	0.89 (0.44–1.8)
RDW-Q3	0.79 (0.37–1.69)	1.34 (0.7–2.55)
RDW-Q4	1.44 (0.7–2.95)	2.06 (1.11–3.83)
P-trend^d	0.39	0.002

BMI body mass index, CI confidence intervals, HR hazard ratio
^aRDW, red cell distribution width levels in quartiles. Quartile cut-off points were 13.2, 13.8, and 14.6%
^bMultivariable adjusted Cox proportional hazards regression model
^cp-value from likelihood ratio test of interaction
^dLinear trend test was performed using median of the quartile as a continuous variable in the Cox proportional hazards regression model