Pre-intervention trend. The dates chosen for the intervention were pre-specified as the date of dissemination of the two regulatory risk communications, which in both cases was at the end of the first quarter of the relevant year. Quarter 2 in 2004 and 2009 were therefore defined as the first post-risk communication time-point. The minimum number of people with dementia being measured in any time point was 1912, and the Title Loaded From File analysis was weighted for the number of patients with dementia included in each time point. The presence of serial autocorrelation was tested for in each model using the Durbin-Watson statistic and the Breusch-Godfrey test, but was not found to be significant in any model. Where appropriate, seasonal effects were accounted for by fitting fixed effects for `quarter’ as an independent variable using Aikake’s Information Criteria to select the best fitting model. Only main effects are presented in the paper.ResultsBetween 2001 and 2011, the total number of patients aged 65 years and over rose from 76,506 to 82,497 with the largest relative increases in the over-85s. The number of patients recorded as having dementia increased from 1912 (prevalence 2.5 of over 65 year olds, 95 CI 2.4?.6) in quarter 1 2001 to 3478 (4.2 , 95 CI 4.1?.4) in quarter 1 2011, which was only partially explained by the rise in the total number of people aged 65 and over, and the very elderly in particular (the dementia prevalence in quarter 1 2011 directly standardised to the quarter 1 2001 population structure was 3.8 (95 CI 3.7?.9)). There were no changes in the rising trend in the prevalence of dementia around the times of the risk communications in 2004 and 2009. Across the entire period, approximately 1 of over-65s were excluded because they had a `severe and enduring mental illness’ diagnosis. The majority of people with dementia were women across the whole time period (75.8 in quarter 1 2001 and 68.9 in quarter 1 2011). Figure 1 shows time trends in the percentage of patients with recorded dementia prescribed any antipsychotic, with segmented regression analysis results for any antipsychotic prescription in table 2. In the segmented regression model, for all antipsychotics, there was a significantly rising trend in antipsychotic prescribingbefore the 2004 risk communication of 0.61 (95 CI 0.53 to 0.68) absolute increase per quarter from a model estimated baseline of 13.9 (table 2). The 2004 risk communication was associated with a large immediate absolute fall in antipsychotic prescribing of 25.94 (95 CI 26.64 to 25.23), with a downward change in trend of 20.54 per quarter (95 CI 20.63 to 20.45) afterwards. The overall effect was therefore of a large immediate drop in prescribing, with a change from a steadily rising trend (an additional 0.61 of people with dementia are prescribed an antipsychotic every quarter) to a flat one (0.61 minus 0.54 = 0.07 increase per quarter). In contrast, the 2009 risk communication was not associated with any immediate reduction in total antipsychotic prescribing, but there was a statistically significant change in trend of 20.51 (95 CI 20.64 to 20.37) per quarter in absolute rates of prescribing, Title Loaded From File equating to a shift from a flat to a falling trend. Figure 1 additionally shows the absolute number of people with recorded dementia prescribed an antipsychotic. Although the immediate changes and changes in trend are broadly mirrored in the absolute numbers prescribed, there were more people with.Pre-intervention trend. The dates chosen for the intervention were pre-specified as the date of dissemination of the two regulatory risk communications, which in both cases was at the end of the first quarter of the relevant year. Quarter 2 in 2004 and 2009 were therefore defined as the first post-risk communication time-point. The minimum number of people with dementia being measured in any time point was 1912, and the analysis was weighted for the number of patients with dementia included in each time point. The presence of serial autocorrelation was tested for in each model using the Durbin-Watson statistic and the Breusch-Godfrey test, but was not found to be significant in any model. Where appropriate, seasonal effects were accounted for by fitting fixed effects for `quarter’ as an independent variable using Aikake’s Information Criteria to select the best fitting model. Only main effects are presented in the paper.ResultsBetween 2001 and 2011, the total number of patients aged 65 years and over rose from 76,506 to 82,497 with the largest relative increases in the over-85s. The number of patients recorded as having dementia increased from 1912 (prevalence 2.5 of over 65 year olds, 95 CI 2.4?.6) in quarter 1 2001 to 3478 (4.2 , 95 CI 4.1?.4) in quarter 1 2011, which was only partially explained by the rise in the total number of people aged 65 and over, and the very elderly in particular (the dementia prevalence in quarter 1 2011 directly standardised to the quarter 1 2001 population structure was 3.8 (95 CI 3.7?.9)). There were no changes in the rising trend in the prevalence of dementia around the times of the risk communications in 2004 and 2009. Across the entire period, approximately 1 of over-65s were excluded because they had a `severe and enduring mental illness’ diagnosis. The majority of people with dementia were women across the whole time period (75.8 in quarter 1 2001 and 68.9 in quarter 1 2011). Figure 1 shows time trends in the percentage of patients with recorded dementia prescribed any antipsychotic, with segmented regression analysis results for any antipsychotic prescription in table 2. In the segmented regression model, for all antipsychotics, there was a significantly rising trend in antipsychotic prescribingbefore the 2004 risk communication of 0.61 (95 CI 0.53 to 0.68) absolute increase per quarter from a model estimated baseline of 13.9 (table 2). The 2004 risk communication was associated with a large immediate absolute fall in antipsychotic prescribing of 25.94 (95 CI 26.64 to 25.23), with a downward change in trend of 20.54 per quarter (95 CI 20.63 to 20.45) afterwards. The overall effect was therefore of a large immediate drop in prescribing, with a change from a steadily rising trend (an additional 0.61 of people with dementia are prescribed an antipsychotic every quarter) to a flat one (0.61 minus 0.54 = 0.07 increase per quarter). In contrast, the 2009 risk communication was not associated with any immediate reduction in total antipsychotic prescribing, but there was a statistically significant change in trend of 20.51 (95 CI 20.64 to 20.37) per quarter in absolute rates of prescribing, equating to a shift from a flat to a falling trend. Figure 1 additionally shows the absolute number of people with recorded dementia prescribed an antipsychotic. Although the immediate changes and changes in trend are broadly mirrored in the absolute numbers prescribed, there were more people with.
