Sex-specific model coefficients for rates of incidentally detected differentiated thyroid cancer by imaging modality, 1998–2017*
| Covariate | Female patients; rate ratio (95% CI) n = 2680† | Male patients; rate ratio (95% CI) n = 1314† |
|---|---|---|
| Imaging modality | ||
| CT | Referent | Referent |
| Carotid ultrasonography | 0.15 (0.10–0.23) | 0.19 (0.12–0.32) |
| MRI | 0.08 (0.05–0.14) | 0.02 (0.01–0.09) |
| SPECT | 0.16 (0.11–0.24) | 0.15 (0.08–0.26) |
| Age group, yr | ||
| 15–19 | 0.09 (0.06–0.14) | 0.06 (0.03–0.12) |
| 20–24 | 0.17 (0.13–0.23) | 0.13 (0.08–0.21) |
| 25–29 | 0.31 (0.25–0.39) | 0.26 (0.19–0.37) |
| 30–34 | 0.50 (0.42–0.61) | 0.38 (0.28–0.52) |
| 35–39 | 0.64 (0.54–0.76) | 0.55 (0.43–0.71) |
| 40–44 | 0.77 (0.65–0.90) | 0.69 (0.54–0.87) |
| 45–49 | 0.89 (0.76–1.03) | 0.83 (0.66–1.04) |
| 50–54 | Referent | Referent |
| 55–59 | 1.01 (0.86–1.18) | 1.06 (0.85–1.32) |
| 60–64 | 1.13 (0.96–1.32) | 1.23 (0.99–1.54) |
| 65–69 | 1.14 (0.97–1.35) | 1.60 (1.28–1.99) |
| 70–74 | 0.97 (0.81–1.17) | 1.46 (1.14–1.85) |
| 75–79 | 1.00 (0.82–1.22) | 1.23 (0.93–1.62) |
| 80–84 | 0.82 (0.65–1.03) | 1.04 (0.74–1.47) |
| Diagnosis period | ||
| 1998–2002 | Referent | Referent |
| 2003–2007 | 1.56 (1.30–1.88) | 1.53 (1.18–1.97) |
| 2008–2012 | 2.61 (2.20–3.09) | 2.59 (2.05–3.26) |
| 2013–2017 | 3.20 (2.71–3.77) | 3.31 (2.64–4.14) |
| Modality (period)‡ | ||
| Carotid ultrasonography (2003–2007)§ | 1.26 (0.77–2.07) | 0.62 (0.31–1.23) |
| Carotid ultrasonography (2008–2012)§ | 1.07 (0.67–1.69) | 0.53 (0.28–1.00) |
| Carotid ultrasonography (2013–2017)§ | 0.89 (0.56–1.40) | 0.59 (0.33–1.06) |
| MRI (2003–2007)§ | 1.97 (1.07–3.60) | 5.25 (1.19–23.15) |
| MRI (2008–2012)§ | 2.20 (1.25–3.88) | 4.64 (1.09–19.80) |
| MRI (2013–2017)§ | 1.99 (1.14–3.49) | 5.21 (1.24–21.84) |
| SPECT (2003–2007)§ | 1.61 (1.01–2.58) | 1.42 (0.72–2.78) |
| SPECT (2008–2012)§ | 1.21 (0.77–1.90) | 1.19 (0.63–2.24) |
| SPECT (2013–2017)§ | 1.24 (0.80–1.92) | 0.65 (0.34–1.24) |
Note: CI = confidence interval, CT = computed tomography, MRI = magnetic resonance imaging, SPECT = single-photon emission computed tomography.
↵* Estimates are for the 3-month look-back period; Appendix 3 (Supplementary Tables 5–6; available at www.cmajopen.ca/content/8/4/E695/suppl/DC1) provides estimates for each look-back period.
↵† Total incidentally detected cases shown to obscure back-calculation of positron emission tomography–associated cases, which were excluded from imaging-specific models because of few cases.
↵‡ Denotes a statistical interaction term among the covariates.
↵§ Denotes the statistical interaction estimate among the covariate categories.