Table 3.
Sensitivity analyses, demonstrating results of the main regression model and alternate models
| All visits | Mean daily visits per clinic at time of lockdown period | Stepwise change in clinic visits/day at start of level 5 lockdown | P value |
| Primary model | 90.3 (67.1 to 113.5) | −6.7 (−16.4 to 3.0) | 0.18 |
| Poisson* mixed effects model | 92.0 (59.3 to 124.7) | −6.9 (−11.0 to −2.8) | 0.001 |
| Linear GEE (exchangeable correlation matrix) | 89.2 (67.0 to 111.4) | −6.4 (−16.8 to 4.08) | 0.23 |
| Poisson GEE* (exchangeable correlation matrix) | 89.2 (84.7 to 93.6) | −6.6 (−8.7 to −4.5) | <0.001 |
| Linear GEE (autoregressive correlation matrix) | 90.2 (73.2 to 107.2) | −5.4 (−27.4 to 16.6) | 0.63 |
| Poisson GEE* (autoregressive correlation matrix) | 88.4 (85.0 to 91.9) | −5.0 (−9.4 to −0.6) | 0.03 |
| Difference-in-differences† | 96.3 (63.6 to 129.0) | 3.4 (−5.5 to 12.4) | 0.45 |
| Childcare visits | |||
| Primary model | 11.9 (8.6 to 15.1) | −7.1 (−8.9 to −5.3) | <0.001 |
| Poisson* mixed effects model | 12.3 (7.1 to 17.5) | −7.7 (−11.1 to −4.4) | <0.001 |
| Linear GEE (exchangeable correlation matrix) | 11.8 (8.6 to 15.0) | −7.1 (−9.0 to −5.2) | <0.001 |
| Poisson GEE* (exchangeable correlation matrix) | 12.0 (10.5 to 13.5) | −7.5 (−8.4 to −6.6) | <0.001 |
| Linear GEE (autoregressive correlation matrix) | 11.9 (9.5 to 14.4) | −6.4 (−9.9 to −2.9) | <0.001 |
| Poisson GEE* (autoregressive correlation matrix) | 11.9 (10.7 to 13.1) | −6.7 (−8.1 to −5.4) | <0.001 |
| Difference-in-differences† | 11.8 (8.0 to 15.7) | −4.0 (−5.5 to −2.5) | <0.001 |
| HIV visits | |||
| Primary model | 37.5 (24.4 to 50.7) | 8.0 (2.3 to 13.7) | 0.01 |
| Poisson* mixed effects model | 39.2 (22.7 to 55.8) | 9.0 (4.5 to 13.5) | <0.001 |
| Linear GEE (exchangeable correlation matrix) | 37.7 (25.3 to 50.1) | 8.1 (2.2 to 14.0) | 0.007 |
| Poisson GEE* (exchangeable correlation matrix) | 37.7 (34.8 to 40.6) | 8.7 (7.2 to 10.3) | <0.001 |
| Linear GEE (autoregressive correlation matrix) | 38.9 (29.3 to 48.5) | 6.1 (−6.2 to 18.5) | 0.33 |
| Poisson GEE* (autoregressive correlation matrix) | 37.9 (35.7 to 40.1) | 5.7 (2.6 to 8.8) | 0.002 |
| Difference-in-differences† | 43.6 (25.1 to 62.1) | 4.8 (−0.5 to 10.1) | 0.08 |
*Poisson GEE results are presented as predictive margins and marginal effects so they represent changes on the same additive scale as the linear models.
†Difference-in-differences estimates are estimated as the mean of the level 5 lockdown period minus the mean of the prelockdown period, comparing 2020 with 2019. Estimates are based on a period-by-year interaction term fit via linear mixed models.
GEE, generalised estimating equations.