Table 2.
Temporal changes in the prescribing of antipsychotic drugs at the time of the national interventions described in Table 1
| Drug type | Predicted proportion prescribed 12 months beforec (%) | Predicted monthly change in proportion prescribed (95% CI)a, p valueb | Predicted proportion prescribed 12 months afterc (%) | Prevalence ratio before/after (95% CI)d | ||
|---|---|---|---|---|---|---|
| 12 months before intervention | During intervention (see Table 1) | 12 months following ‘during’ the intervention period | ||||
| UK MHRA Committee for the Safety of Medicines, warning March 2004 | ||||||
| All antipsychotic drugs | 17.6 | 0.07 (−0.00 to 0.14) | −1.69 (−1.88 to −1.51) PD < 0.001 |
0.04 (0.00–0.08) PA < 0.001 |
15.8 | 0.81 (0.76–0.87) |
| First-generation antipsychotic drugs | 5.5 | −0.12 (−0.14 to −0.10) | 0.40 (0.27 to 0.53) PD < 0.001 |
0.03 (0.01–0.05) PA < 0.001 |
6.5 | 1.17 (1.03–1.31) |
| Second-generation antipsychotic drugs | 12.6 | 0.19 (0.13–0.23) | −2.27 (−2.59 to −1.95) PD < 0.001 |
0.01 (−0.01 to 0.04) PA < 0.001 |
9.7 | 0.66 (0.61–0.71) |
| Risperidone | 8.9 | 0.04 (0.01–0.07) | −1.98 (−2.36 to −1.61) PD < 0.001 |
−0.17 (−0.23 to −0.12) PA < 0.001 |
1.9 | 0.48 (0.43–0.53) |
| Olanzapine | 2.6 | 0.08 (0.06–0.10) | −0.62 (−0.65 to −0.58 PD < 0.001 |
−0.04 (−0.05 to −0.03) PA < 0.001 |
1.3 | 0.60 (0.51–0.70) |
| Quetiapine | 0.9 | 0.06 (0.05–0.07) | 0.24 (0.18–0.30) PD < 0.001 |
0.18 (0.14–0.22) PA = 0. 17 |
5.2 | 1.51 (1.24–1.83) |
| Amisulpride | 0.3 | 0.01 (0.00 to 0.01) | 0.07 (0.04–0.11) PD < 0.001 |
0.04 (0.03–0.05) PA = 0.05 |
1.27 | 1.47 (1.00–2.15) |
| NICE guidelines, November 2006 | ||||||
| All antipsychotic drugs | 16.2 | 0.04 (0.00–0.09) | 0.20 (−0.26 to 0.67) PD = 0. 51 |
0.10 (0.04–0.16) PA = 0.67 |
14.1 | 1.07 (1.01–1.13) |
| First-generation antipsychotic drugs | 6.2 | −0.06 (−0.08 to 0.03) | 0.03 (−0.16 to 0.21) PD = 0. 40 |
0.00 (−0.02 to 0.01) PA = 0.75 |
5.6 | 1.02 (0.93–1.12) |
| Second-generation antipsychotic drugs | 10.3 | 0.10 (0.07 to 0.13) | 0.21 (−0.09 to 0.52) PD = 0. 46 |
0.11 (0.07–0.16) PA = 0.52 |
13.0 | 1.08 (1.01–1.15) |
| Risperidone | 2.0 | −0.03 (−0.04 to −0.02) | −0.01 (−0.06 to 0.03) PD = 0. 61 |
0.00 (−0.00 to 0.01) PA = 0.43 |
1.6 | 0.87 (0.74–1.03) |
| Olanzapine | 1.3 | −0.01 (−0.01 to 0.01) | 0.02 (−0.03 to 0.07) PD = 0. 25 |
−0.00 (−0.01 to 0.01) PA = 0.45 |
0.9 | 0.97 (0.80–1.17) |
| Quetiapine | 5.6 | 0.12 (010–0.13) | 0.21 (−0.02 to 0.43) PD = 0. 43 |
0.10 (0.07–0.13) PA = 0.34 |
6.6 | 1.14 (1.05–1.24) |
| Amisulpride | 1.0 | 0.02 (0.01–0.03) | 0.00 (−0.01 to 0.002) PD = 0. 03 |
0.01 (0.01–0.01) PA = 0.38 |
1.4 | 1.10 (0.92–1.31) |
| UK MHRA drug safety updates, March and June 2009, expert review October 2009, government pledge November 2009 | ||||||
| All antipsychotic drugs | 17.8 | −0.09 (−0.21 to −0.03) | −0.16 (−0.21 to −0.12) PD = 0.08 |
−0.14 (−0.18 to −0.01) PA = 0.53 |
12.6 | 0.83 (0.79–0.88) |
| First-generation antipsychotic drugs | 5.2 | −0.05 (−0.07 to −0.03) | -0.07 (−0.08 to −0.05) PD = 0.10 |
−0.05 (−0.06 to −0.05) PA = 0.13 |
3.2 | 0.85 (0.77–0.95) |
| Second-generation antipsychotic drugs | 12.9 | −0.05 (−0.10 to −0.00) | −0.10 (−0.14 to −0.06) PD = 0.12 |
−0.09 (−0.13 to −0.06) PA = 0.80 |
9.7 | 0.84 (0.79–0.90) |
| Risperidone | 1.6 | −0.02 (−0.02 to −0.01) | −0.02 (−0.02 to −0.01) PD = 0.52 |
0.05 (0.04–0.06) PA < 0.001 |
1.8 | 0.73 (0.61–0.87) |
| Olanzapine | 1.1 | −0.02 (−0.03 to −0.01) | −0.01 (−0.02 to −0.00) PD = 0.19 |
0.00 (−0.00 to 0.01) PA = 0.005 |
0.8 | 0.81 (0.66–1.00) |
| Quetiapine | 8.4 | 0.01 (−0.04 to 0.03) | −0.07 (−0.11 to −0.04) PD = 0.008 |
−0.12 (−0.14 to −0.09) PA = 0.07 |
5.8 | 0.87 (0.81–0.94) |
| Amisulpride | 1.8 | −0.02 (−0.02 to −0.01) | 0.00 (−0.00 to 0.01) PD < 0.001 |
−0.03 (−0.04 to −0.03) PA < 0.001 |
1.0 | 0.92 (0.78–1.09) |
| National Dementia Challenge March 2012, MHRA drug safety update May 2012 | ||||||
| All antipsychotic drugs | 12.4 | −0.19 (−0.22 to −0.15) | −0.16 (−0.23 to −0.09) PD = 0.54 |
−0.06 (−0.08 to −0.04) PA = 0.01 |
8.6 | 0.86 (0.81–0.92) |
| First-generation antipsychotic drugs | 3.1 | −0.06 (−0.07 to −0.05) | −0.03 (−0.06 to −0.01) PD = 0.05 |
−0.05 (−0.05 to −0.04) PA = 0.39 |
1.7 | 0.81 (0.71–0.91) |
| Second-generation antipsychotic drugs | 9.4 | −0.13 (−0.15 to −0.10) | −0.13 (−0.19 to −0.08) PD = 0.84 |
−0.01 (−0.03 to −0.00) PA < 0.001 |
7.1 | 0.89 (0.83–0.95) |
| Risperidone | 1.8 | 0.02 (0.01–0.03) | 0.02 (0.00–0.04) PD = 0.87 |
0.03 (0.02–0.04) PA = 0.30 |
2.6 | 1.13 (0.99–1.29) |
| Olanzapine | 0.8 | −0.01 (−0.01 to −0.00) | −0.01 (−0.01 to 0.00) PD = 0.71 |
−0.00 (−0.01 to 0.00) PA = 0.30 |
0.7 | 0.93 (0.76–1.14) |
| Quetiapine | 5.6 | −0.11 (−0.13 to −0.09) | −0.12 (−0.14 to −0.10) PD = 0.34 |
−0.04 (−0.05 to −0.03) PA < 0.001 |
3.0 | 0.80 (0.74–0.88) |
| Amisulpride | 1.0 | −0.03 (−0.03 to −0.02) | −0.02 (−0.03 to −0.02) PD = 0.54 |
−0.01 (−0.01 to −0.00) PA = 0.004 |
0.5 | 0.80 (0.64–0.99) |
CI confidence interval, MHRA Medicines Healthcare products Regulatory Agency, NICE National Institute for Health and Care Excellence
aPredicted monthly change is the absolute value not relative to the starting prevalence, e.g., for row 1 the starting prevalence is 17.6%, which increases by 0.08 per month making a value of 17.68% in the following month, assuming a linear trend (for illustration only, the method does not assume a linear trend)
b p value tests null hypothesis that there is no difference in the monthly change in receiving at least one prescription before and after the intervention using a cut-off point of the start of the intervention period (i.e., PD compares ‘during and after’ with ‘before’) or using a cut-offpoint of the end of the intervention period (i.e., PA compares ‘after’ with ‘before and during’)
cPredicted proportion (%) of patients prescribed at least one antipsychotic drug during the month exactly 12 months before the intervention or at the end of the observation period (Table 1)
dPrevalence ratio compares repeated prescribing for 3 months or longer during the 6 months after the intervention relative to the 6 months leading up to the intervention as defined in Table 1