Table 4. Excess relative risk (ERR) estimates (and 95% confidence intervals (CI)) and adjustment factors for circulatory disease mortality endpoints (and 95% CI) for 0–0.5 Gy dose range in models that adjust for (a) age at first exposure, (b) years since last exposure or (c) radiation dose rate.
| Type of adjustment to ERR/Gy | Excess relative risk/Gy (+95% CI)/% adjustment (+95% CI)/p-value | |||||
|---|---|---|---|---|---|---|
| All circulatory disease | IHD | Cerebrovascular | Hypertensive | Heart disease apart from IHD and hypertensive | All other circulatory diseases apart from heart and cerebrovascular | |
| Linear ERR/Gy adjusted for age at first exposure | 0.165 (0.013, 0.478) | 0.214 (−0.088a, 0.544) | 0.510 (−0.159a, 1.242) | 1.166 (−0.688a, 3.456) | −0.236 (−0.664, 0.309a) | 0.461 (−0.621a, 1.688) |
| Age at first exposure adjustment (% change in ERR/Gy per year of age at first exposure) | −13.0 (−25.8, 8.5) | 3.2 (−32.5, 25.9) | −4.3 (−18.3a, 12.1a) | −0.8 (−14.2a, 14.6a) | 3.6 (−7.9a, 16.7a) | 1.2 (−13.2a, 17.9a) |
| p-valueb for modification of ERR | 0.251 | 0.552 | 0.593 | 0.890 | 0.353 | 0.899 |
| Linear ERR/Gy adjusted for time since last exposure | 0.272 (−0.024a, 0.582) | 0.215 (−0.109a, 0.659) | 0.540 (−0.203a, 1.338) | 1.047 (−0.824a, 3.179) | −0.215 (−0.701, 0.408) | 0.007 (−0.059a, 1.387) |
| Years since last exposure adjustment (% change in ERR/Gy per year since last exposure) | −10.5 (−49.2, −3.9) | −14.7 (−42.6, −6.4) | −6.1 (−17.3a, 6.5a) | 1.6 (−8.5a, 13.0a) | 0.6 (−14.2a, 17.9a) | 21.6 (−7.9a, 60.6a) |
| p-valueb for modification of ERR | 0.002 | < 0.001 | 0.402 | 0.693 | 0.899 | 0.244 |
| Linear ERR/Gy adjusted for dose rate | 0.247 (0.036, 0.470) | 0.268 (−0.014a, 0.551) | 0.467 (−0.101, 1.117) | 1.108 (−0.633a, 3.220) | −0.228 (−0.678, 0.379a) | 0.500 (−0.467a, 1.535) |
| Dose rate adjustment (% change in ERR/Gy per Gy/year) | 3.11 (−95.85, 67.50) | −19.32 (−99.28, 60.32) | 32.51 (−30.36a, > 100a) | −20.05 (−98.62a, > 100a) | −59.51 (−99.98a, > 100a) | −22.65 (−99.63a, > 100a) |
| p-valueb for modification of ERR | 0.950 | 0.684 | 0.565 | 0.877 | 0.570 | 0.847 |
aWald-based CI.
b2-sided p-value for departure of trend from null.
All models adjust for cohort/sub-cohort, gender, smoking status, tuberculosis status, attained age, calendar year at risk by stratification. All CI are profile-likelihood based. The adjustments for age at first exposure, years since last exposure and dose rate are centered at the person-year-weighted mean values for the <0.5 Gy data, namely 27.98 years, 25.09 years and 0.61 Gy/year, respectively. 5 year dose lag and period from entry to start of follow-up. Unless otherwise stated all CI are based on the profile likelihood.