Segmented Regression Model Parameters Showing the Year-to-Year Trend in Cancer Screening Rates Before and After Introduction of Ontario’s Preventive Care Incentives In 2006–2007
| Type of Cancer Screening | Intercept (β0) % (95% CI) | Baseline Trend Before Incentives (β1) % (95% CI) | Step Change After Introduction of Incentives (β2) % (95% CI) | Trend Change After Introduction of Incentives (β3) % (95% CI) | Trend After Introduction of Incentives ( β1+ β3) % (95% CI) |
|---|---|---|---|---|---|
| Cervical | 53.9 (52.5 to 55.3) | 0.26 (−0.054 to 0.57) | 1.5 (−0.80 to 3.8) | −0.21 (−1.0 to 0.59) | 0.045 (−0.70 to 0.79) |
| Breast | 60.9 (59.7 to 62.0) | −0.24 (−0.49 to 0.015) | 1.6 (−0.25 to 3.5) | 0.72 (0.080 to 1.4) | 0.49 (−0.10 to 1.1) |
| Colorectal | 17.2 (15.0 to 19.5) | 3.0 (2.3 to 3.7) | 0.95 (−2.2 to 4.1) | 1.7 (0.55 to 2.9) | 4.7 (3.7 to 5.7) |
Note: The segmented linear regression models are Yt= β0 +β1*timet +β2*interventiont +β3*time after interventiont +et, where Yt stands for observed series and et represents an error term. These regression models allow for a linear trend before intervention, a step change after intervention, and a linear trend change after intervention.