The impact of the licensing changes on prescribing of NRT to CVD patients CVD patients

Data from THIN were used to explore patterns in prescribing of NRT to patients with CVD in England between January 2002 and June 2009 and to establish whether the broadening of the indications led to an increase in prescribing of NRT to patients with coronary heart disease (CHD) and medication to patients in England who were aged 16 and over with CHD or stroke. The main outcome measures were the number of patients per 100,000 with CHD and stroke that received a prescription for NRT each month. From the THIN database all adult (16+) CHD and stroke patients contributing data each month between January 2002 and June 2009 were identified using Read Codes based on the definitions of these diseases from the QOF.¹⁸⁸ As described in section 1.6.9, the QOF sets out requirements for the management of smoking in patients with certain chronic diseases, and these include CVD. The CHD and stroke patients with a prescription for

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NRT in each month during the study period were also identified. The rates of prescribing per 100,000 CHD and stroke patients were calculated using the procedure described in section 3.2.

It is possible that varenicline may have substituted for some of the use of NRT in CVD patients after it was introduced in December 2006.

Therefore, in order to examine trends in total prescribing of all licensed smoking cessation medications to this patient group (i.e. NRT, varenicline and bupropion), data on prescribing of these to CHD and stroke patients were also extracted. Rates of prescribing were calculated as described above.

Data on prescribing to adults with recorded hypertension (a major risk factor for CVD), asthma and chronic obstructive pulmonary disease (COPD), as well as prescribing to the rest of the adult population were also extracted, in order to compare prescribing to CVD patients with that to groups for which the licensing for NRT did not change in November 2005.²⁶⁹ Due to incompleteness in the recording of smoking status in THIN until 2006, we were unable to look at prescribing in smokers only for the whole time course of the study.¹⁸⁴ However, we used data from 2007 and 2008 (when the majority of patients in THIN had their smoking status recorded) to calculate average rates of prescribing per month in smokers with CHD and stroke and compare this with rates of prescribing in other disease groups, and in the rest of the population, in 2007 and 2008.¹⁸⁴ The data on patients with hypertension, asthma and COPD were also identified using Read Codes based on the definitions of these diseases from the QOF.

166 Analysis

The trend in prescribing following the licensing change appeared to be linear, and a segmented regression analysis was therefore carried out using GAMMs to estimate the effect of the broadening of the indications on rates of prescribing of NRT to patients with CHD and stroke, using the procedure described in section 4.3.1 and applied in section 6.2. GAMMs were also built for total prescribing (NRT, varenicline and bupropion) to explore overall trends in prescribing for smoking cessation medication during the study period.

6.3.2 Results

Data were available on up to 88,000 CHD patients and 39,000 stroke patients each month. Figure 6-4 shows the rates of prescribing of NRT to CHD and stroke patients during the study period. As in the general population (shown in Chapters 3 and 5), in most years there was a peak in prescribing in January and March, coinciding with the New Year and No Smoking Day, and the time series plot suggests an increase in prescribing of NRT up to 2006 with a reduction in subsequent years. Figure 6-4 also shows the fitted trends from the segmented regression modelling for prescribing of NRT, the results of which are also presented in Table 6-2.

There was no statistically significant immediate step change in the level of prescribing following the licensing change; therefore, this term was omitted from the model. Table 6-2 shows the baseline trend in prescribing (the monthly change in the number of people receiving prescriptions per 100,000 before the licensing change) and the change in the trend in the monthly number of CHD and stroke patients receiving prescriptions per 100,000 following the broadening of indications, compared with the baseline trend.

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Figure 6-4. Rates of prescribing of NRT and fitted trends in CHD and stroke patients before and after the NRT licensing change, England, based on THIN, January 2002-June 2009

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Table 6-2. Results of segmented regression analysis of the impact of the broadening of the indications for NRT on prescribing of NRT to CVD patients Note: only parameters significant in parsimonious model included

1: monthly change in number of prescription per 100,000 patients before licensing change

2: step change in the monthly level of prescribing immediately after licensing change

3: absolute change in trend in monthly numbers of prescriptions per 100,000 patients after licensing change, compared with baseline trend ( 1 + 3 = post-intervention trend)

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In CHD patients, the number of people receiving prescriptions for NRT was increasing at the rate of 3.18 per 100,000 patients per month between January 2002 and the broadening of indications in 2005 (95% CI 2.15-4.21, p<0.0001) (Table 6-2). There was no immediate step change in the level of prescribing following the licensing change, but after 2005 there was a significant change in trend (p<0.0001) representing a decrease in the rate of prescribing.

A similar trend was observed in stroke patients. In this group, the number of people receiving NRT prescriptions was increasing by 3.37 per 100,000 patients per month before the broadening of the indications (95%

CI 2.31-4.43, p<0.0001) (Table 6-2 and Figure 6-4). There was no immediate step change in the level of prescribing following the licensing change, but there was a significant change in trend (p<0.0001) such that there was a decreasing trend in prescribing.

Figure 6-5 shows the rates of prescribing of all smoking cessation medications combined (NRT, varenicline and bupropion) in CHD and stroke patients during the study period, and the results of the segmented regression modelling are also presented in Table 6-2. Figure 6-5 shows that overall prescribing of this group of medications to both CHD and stroke patients increased until 2005 and remained fairly stable in the latter part of the study period. The rate of prescribing for bupropion decreased during the study period and was extremely low in the final years of the study; generally, only between five and ten patients per 100,000 received a prescription for bupropion each month in the period following the

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introduction of varenicline (not shown). The majority of prescriptions were therefore for NRT and, after December 2006, NRT and varenicline.

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Figure 6-5. Rates of prescribing of all smoking cessation medications (NRT, varenicline and bupropion) and fitted trends in CHD and stroke patients before and after the licensing change, England, based on THIN, January 2002-June 2009

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Figure 6.6 shows the average rate of prescribing of NRT to smokers with CHD, stroke, hypertension, asthma, COPD and without one of these diseases per month in 2007 and 2008. Prescribing was highest to smokers with COPD, at around 2500 per 100,000 smokers per month, and very similar in those with CHD, stroke and asthma, at around 1500 per 100,000 smokers per month. Prescribing of NRT to the rest of the population was about a third of that to smokers with CHD and stroke.

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Figure 6-6. Number of smokers with NRT prescriptions per month by disease group, England, based on THIN, 2007 and 2008

174 6.3.3 Discussion

To my knowledge this is the first study into rates of prescribing of NRT to individuals with cardiovascular disease. Like the previous study in this chapter, the major strengths of this study are the use of validated, large-scale data, and the use of segmented regression analysis to estimate changes in the level and trend of NRT prescribing following the licensing change.

This study found that prescribing of NRT to CHD and stroke patients increased until the end of 2005 and subsequently decreased, with no immediate change following the MHRA licensing change. In 2007 and 2008 rates of prescribing of NRT to smokers with CVD were similar to that to status data in THIN prior to 2006.¹⁸⁴ However, as explained in section 5.4, the small annual decreases in adult smoking prevalence during the study period are likely to have made a negligible contribution to the monthly changes in rates of prescribing observed in this study.

Similarly, as explained in earlier parts of this thesis, THIN smoking cessation medication prescribing data may underestimate the supply of stop smoking medication provided by health professionals, though it is unlikely that this has influenced trends in prescribing in a way that could have had an impact on the results of this study.

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Like the other policy evaluation studies presented so far in this thesis, this study also does not include NRT purchased over-the-counter (OTC). However, it is unlikely that a sudden switch to OTC NRT has contributed to changes in prescribing of NRT during the study period, as NRT has been available OTC since 1999. In addition to this, smokers with CVD may be less likely to use OTC NRT, and more likely to seek medical advice before using NRT and therefore receive NRT on prescription. To my knowledge, there was no media publicity about the licensing change which is likely to have reassured patients with CVD that they could start buying NRT OTC rather than seeking the advice of a health professional.

The results of this study suggest that only a small proportion of smokers with CVD are receiving smoking cessation support in primary care, despite overwhelming reasons for them to stop smoking. The study found that 1500 per 100,000 smokers (1.5%) with CVD receive a prescription for NRT per month. This suggests that a maximum of 18% of smokers with CVD are obtaining a prescription for NRT each year; as quitting episodes may last longer than a month, it is likely that the actual percentage is even lower. The rate of prescribing of NRT in CVD patients therefore seems low. It is not known what proportion of smokers with CVD attempt to quit each year, but in the general population in England 36% of adults reported having made a quit attempt in the past year in 2010.²⁷⁰ Given the immediate health risks, it seems likely that the rate is much higher in CVD patients, and the rate of prescribing to these patients therefore seems low as a proportion of CVD patients who try to quit as well as overall. This study therefore suggests that opportunities to help these smokers quit are being missed.

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Removing the barriers to health professionals prescribing NRT to patients with CVD may have been expected to increase prescribing of this medication to this group, either as a result of GPs being more willing to prescribe to a group perceived as high risk, or as a result of these patients being more willing to use it. We found no immediate increase in prescribing following the change in indications, and that in the period following the licensing change, prescribing in this disease group declined. As in the previous study in this thesis, this seems particularly surprising given the introduction of the smoking ban in this period, which may also have been expected to increase prescribing. This apparent decline seems unlikely to be due to the broadening of indications for NRT on the basis of evidence that it is safe in this group. Furthermore, the decreasing trend in prescribing for NRT is similar to that observed in the general population in the study in Chapter 5. It therefore seems likely that factors other than the licensing change, which are common to the majority of patients to whom NRT is prescribed, have led to a widespread decrease in prescribing for NRT from 2006 onwards.

One possible explanation for the decrease in prescribing of NRT may be substitution by varenicline, which became available on NHS prescription a year following the licensing change and which, as shown in Chapter 5, rapidly became the second most popular smoking cessation medication. It is possible that varenicline, which had not yet been tested in CVD patients when it became available but seemed likely to have no cardiovascular effects, may have substituted for some of the use of NRT in CVD patients.²⁷¹ Our results showed that, despite the decrease in prescribing for NRT in the period following the licensing change, overall prescribing for smoking cessation medication remained fairly stable, indicating that the

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decrease in NRT prescribing was at least partly offset by prescribing for varenicline. It is not known whether varenicline halted an overall decline in prescribing of smoking cessation medication in this patient group, or whether it substituted for some prescribing of NRT. Either way, however, it appears that, overall, prescribing for smoking cessation medication to CVD patients has not reduced in recent years.

Despite the lack of increase in prescribing of NRT to CVD patients, it is likely, as was highlighted in the previous study, that there were benefits of the licensing change that could not be observed in this study in terms of reassuring GPs who prescribe NRT to CVD patients, and non-prescribers who provide advice about its use.

6.3.4 Conclusions this group of patients has declined since 2005, although the reduction may have been offset by a rapid increase in prescribing for varenicline. As such, it appears that opportunities for smoking cessation intervention in primary care patients with CVD are being missed.