Table 1. Interrupted time-series analysis of LARC prescribing rates in general practices.
| LARC (95% CI) | Injectable (95% CI) | Implant (95% CI) | IUS (95% CI) | IUCD (95% CI) | |
| Time | 0.99 (0.98,1.02) | 0.98 (0.96,0.99) | 1.64 (1.49,1.80) | 1.19 (1.11,1.28) | 1.04 (0.98,1.11) |
| QOF | 0.99 (0.97, 1.02) | 0.99 (0.96, 1.01) | 1.20 (1.09, 1.32) | 0.97 (0.90, 1.04) | 1.02 (0.94, 1.10) |
| Time after QOF | 1.04 (1.03, 1.06) | 1.06 (1.04, 1.08) | 1.34 (1.13, 1.58) | 1.11 (0.97, 1.26) | 0.99 (0.93, 1.05) |
| Seasonality | |||||
| Apr-Jun | – | – | – | – | – |
| Jul-Sep | 0.97 (0.96, 0.99) | 0.98 (0.97, 0.99) | 0.95 (0.91, 1.00) | 0.93 (0.89, 0.96) | 0.95 (0.90, 1.01) |
| Oct-Dec | 0.97 (0.95, 0.98) | 0.98 (0.96, 0.99) | 0.93 (0.88, 0.98) | 0.91 (0.88, 0.95) | 0.94 (0.89, 1.00) |
| Jan-Mar | 0.98 (0.96, 0.99) | 0.98 (0.97, 1.00) | 1.02 (0.97, 1.07) | 0.94 (0.91, 0.98) | 1.01 (0.95, 1.07) |
| Socioeconomic status | |||||
| Quintile 1 (the most affluent) | – | – | – | — | — |
| Quintile 2 | 1.21 (1.05, 1.39) | 1.30 (1.11, 1.51) | 1.32 (1.08, 1.60) | 1.02 (0.81, 1.29) | 1.21 (0.91, 1.61) |
| Quintile 3 | 1.33 (1.14, 1.55) | 1.49 (1.26, 1.75) | 1.23 (0.98, 1.54) | 0.75 (0.57, 0.97) | 1.40 (1.01, 1.93) |
| Quintile 4 | 1.64 (1.40, 1.93) | 1.81 (1.52, 2.16) | 1.14 (0.91, 1.44) | 0.65 (0.49, 0.85) | 1.10 (0.79, 1.54) |
| Quintile 5 (the most deprived) | 1.05 (0.88, 1.25) | 1.04 (0.86, 1.25) | 1.26 (0.96, 1.65) | 0.43 (0.32, 0.59) | 1.07 (0.74, 1.56) |
| Residence | |||||
| Rural | — | — | — | — | — |
| Urban | 0.77 (0.66, 0.91) | 0.84 (0.71, 0.99) | 0.43 (0.35, 0.54) | 0.55 (0.42, 0.72) | 0.45 (0.32, 0.63) |
| White British (%) | 1.01 (1.00, 1.01) | 1.01 (1.00, 1.01) | 1.00 (1.00, 1.01) | 1.01 (1.00, 1.01) | 1.00 (0.99, 1.00) |
| Female GP in the Practice | |||||
| Without Female GP | – | – | – | – | – |
| With Female GP | 2.03 (1.82, 2.27) | 1.81 (1.61, 2.04) | 2.40 (1.95, 2.97) | 1.81 (1.46, 2.25) | 2.26 (1.76, 2.90) |
Note: LARCs (Long-Acting Reversible Contraceptives), IUS (Intra-uterine system), IUCD (Intra-uterine copper devise).
‡
Model also controlled for regional variables (Primary Care Trust dummy variables), results not shown.
‡
As the linearity of the time trend was not met for implant and IUS outcomes, quadratic term for the time variable was added in the model.The beta coefficients are 0.91 (95% CI = 0.89, 0.94) for implant, and 0.97 (95% CI = 0.95, 0.99) for IUS.