Table 3

Results of interrupted time series analysis of the impact of reducing and abolishing prescription fees in Scotland on hospital admissions (incidence rate ratios) and prescribed medicines (defined daily doses and cost)

InterceptMonthly changeReduction step changeReduction change in slopeAbolition step changeAbolition change in slope
Admissions IR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CI
 Intervention1.01e-2 9.46e-3 to 1.09e-2 1.001.00 to 1.011.030.98 to 1.080.990.99 to 0.990.810.72 to 0.901.000.99 to 1.00
 Age-c’fact6.65e-2 6.36e-2 to 6.95e-2 1.001.00 to 1.001.031.01 to 1.061.000.99 to 1.000.950.90 to 1.001.000.99 to 1.00
 Condition-c’fact4.80e-3 4.39e-3 to 5.24e-3 1.001.00 to 1.010.950.88 to 1.031.001.00 to 1.011.010.86 to 1.201.001.00 to 1.01
Admissions 1-month lag IR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CI
 Intervention1.02e-2 9.49e-3 to 1.09e-2 1.011.00 to 1.011.010.96 to 1.060.990.99 to 0.990.780.71 to 0.871.000.99 to 1.00
 Age-c’fact6.74e-2 6.45e-2 to 7.05e-2 1.001.00 to 1.001.031.01 to 1.061.000.99 to 1.000.950.90 to 1.001.000.99 to 1.00
 Condition-c’fact4.83e-3 4.41e-3 to 5.28e-3 1.001.00 to 1.000.980.91 to 1.061.001.00 to 1.001.070.91 to 1.261.001.00 to 1.01
Admissions 2-month lag IR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CI
 Intervention1.02e-2 9.51e-3 to 1.09e-2 1.001.00 to 1.011.010.96 to 1.060.990.99 to 0.990.790.71 to 0.871.000.99 to 1.00
 Age-c’fact6.77e-2 6.47e-2 to 7.07e-2 1.001.00 to 1.001.041.02 to 1.071.000.99 to 1.000.970.92 to 1.021.001.00 to 1.00
 Condition-c’fact4.85e-3 4.44e-3 to 5.30e-3 1.001.00 to 1.000.990.92 to 1.071.001.00 to 1.011.100.93 to 1.281.001.00 to 1.01
Admissions 3-month lag IR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CIIRR95% CI
 Intervention1.02e-2 9.49e-2 to 1.09e-2 1.011.00 to 1.010.990.94 to 1.040.990.99 to 0.990.780.70 to 0.861.000.99 to 1.00
 Age-c’fact6.73e-2 6.44e-2 to 7.04e-2 1.001.00 to 1.001.021.00 to 1.051.000.99 to 1.000.940.90 to 0.991.001.00 to 1.00
 Condition-c’fat4.82e-3 4.41e-3 to 5.26e-3 1.001.00 to 1.000.970.90 to 1.051.001.00 to 1.011.080.92 to 1.261.001.00 to 1.00
DDDs DDDs95% CIΔDDDs95% CIΔDDDs95% CIΔDDDs95% CIΔDDDs95% CIΔDDDs95% CI
 Intervention29.6528.71 to 30.59−0.04−0.06 to −0.02−0.11−0.61 to 0.390.040.02 to 0.076.034.94 to 7.130.100.08 to 0.13
 Age-c’fact100.8898.07 to 103.70−0.05−0.11 to 0.015.063.61 to 6.520.680.59 to 0.7738.3734.84 to 41.900.340.25 to 0.42
 Condition-c’fact55.6153.70 to 57.530.140.10 to 0.18−1.88−2.90 to −0.85−0.05−0.11 to 0.006.023.73 to 8.320.150.09 to 0.20
Cost £s95% CIΔ£s95% CIΔ£s95% CIΔ£s95% CIΔ£s95% CIΔ£s95% CI
 Intervention19.3618.53 to 20.190.160.15 to 0.180.23−0.19 to 0.66−0.15−0.17 to −0.13−0.96−1.92 to −0.01−0.10−0.12 to −0.08
 Age-c’fact69.9267.35 to 72.490.620.56 to 0.684.743.42 to 6.060.03−0.05 to 0.1214.2410.86 to 17.63−0.36−0.44 to −0.28
 Condition-c’fact26.3525.35 to 27.340.150.13 to 0.17−3.16−3.70 to −2.62−0.01−0.04 to 0.022.000.79 to 3.20−0.11−0.14 to −0.08
  • c’fact, counterfactual; DDDs, defined daily doses per 100 patients per practice per month; ΔDDDs, change in DDDs; IR, incidence rate per 100 patients per practice per month; IRR, incidence rate ratio; £s, gross ingredient cost of medicines before any discount per 100 patients per practice per month; Δ£s, change in £s.