Table 4.
Incidence rate ratios (RR) of neurodegenerative disease (1992-2018) by McIntyre Powder (MP) exposure assessed from historical records (periods and duration of exposure and time since last exposure) among male miners in the study cohort. [CI=95% confidence interval] a
| MP exposure assessment: Historical Records | Alzheimer’s disease | Alzheimer’s with other dementias | Parkinson’s disease | Parkinsonism | Motor neuron disease | |||||
|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
|
||||||
| Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | Cases | RR (95% CI) | |
| MP Unexposed | 554 | 1.00 (‥) | 3004 | 1.00 (‥) | 360 | 1.00 (‥) | 605 | 1.00 (‥) | 55 | 1.00 (–) |
| MP exposed | 313 | 0.95 (0.82–1.09) | 2011 | 1.14 (1.08–1.21) | 284 | 1.32 (1.13–1.54) | 426 | 1.18 (1.04–1.33) | 26 | 0.80 (0.50–1.28) |
| Only before 1956 | 54 | 1.00 (0.75–1.32) | 283 | 1.11 (0.98–1.26) | 39 | 1.22 (0.87–1.71) | 57 | 1.25 (0.94–1.65) | <6 | ‥ |
| Ever after 1956 | 259 | 0.94 (0.81–1.09) | 1728 | 1.15 (1.08–1.22) | 245 | 1.34 (1.14–1.57) | 369 | 1.17 (1.02–1.33) | 26 | 0.88 (0.55–1.40) |
| Only after 1956 | 143 | 0.93 (0.77–1.13) | 1028 | 1.13 (1.05–1.21) | 143 | 1.33 (1.09–1.62) | 230 | 1.14 (0.98–1.33) | 21 | 0.97 (0.58–1.61) |
| Duration of MP exposure | ||||||||||
| >0–1 year | 57 | 0.95 (0.72–1.24) | 417 | 1.18 (1.06–1.30) | 52 | 1.23 (0.92–1.65) | 88 | 1.12 (0.90–1.41) | 10 | 1.16 (0.59–2.29) |
| >1–5 years | 84 | 0.89 (0.71–1.12) | 591 | 1.14 (1.04–1.24) | 80 | 1.28 (1.01–1.63) | 124 | 1.15 (0.95–1.40) | 6 | 0.58 (0.25–1.35) |
| >5–10 years | 73 | 0.96 (0.75–1.22) | 428 | 1.07 (0.96–1.18) | 65 | 1.32 (1.02–1.73) | 88 | 1.09 (0.87–1.36) | <6 | ‥ |
| >10 years | 99 | 1.00 (0.80–1.23) | 575 | 1.18 (1.08–1.30) | 87 | 1.42 (1.12–1.80) | 126 | 1.32 (1.09–1.61) | 7 | 1.05 (0.48–2.34) |
| The P-value for linear trend | 0.995 | 0.001 | 0.003 | 0.007 | 0.695 | |||||
| Time since last MP exposure | ||||||||||
| 12–19 years | 6 | 0.49 (0.22–1.10) | 79 | 1.22 (0.97–1.53) | 10 | 1.05 (0.55–1.99) | 34 | 1.51 (1.06–2.15) | <6 | ‥ |
| 20–29 years | 37 | 0.80 (0.57–1.11) | 298 | 1.21 (1.07–1.36) | 45 | 1.38 (1.00–1.89) | 80 | 1.22 (0.96–1.54) | 6 | 0.94 (0.40–2.22) |
| 30–39 years | 90 | 0.99 (0.80–1.24) | 600 | 1.17 (1.07–1.28) | 96 | 1.50 (1.20–1.88) | 147 | 1.23 (1.03–1.48) | 13 | 1.11 (0.61–2.05) |
| 40–49 years | 104 | 0.95 (0.77–1.18) | 631 | 1.14 (1.04–1.24) | 87 | 1.27 (1.01–1.61) | 115 | 1.10 (0.90–1.34) | <6 | ‥ |
| 50–75 years | 76 | 1.05 (0.82–1.34) | 403 | 1.05 (0.95–1.17) | 46 | 1.14 (0.83–1.56) | 50 | 1.01 (0.75–1.36) | <6 | ‥ |
a
All estimates are from Poisson regression models adjusted for age, age2, and birth year throughout the follow-up period. The P-value for linear trend was derived from Poisson regression models.