ABSTRACT

Background

To report the trends in the use and costs of anti-obesity medications in England from 1998 to 2005.

Methods

We analysed data on all community anti-obesity drug prescriptions in England collated by the prescription cost analysis system.

Results

Between 1998 and 2005, Orlistat prescriptions rose 36-fold from 17,880 to 646,700 and total cost increased by over 35-fold. Sibutramine prescriptions rose from 2001 to 2005 from 53,393 to 227,000, a 4-fold increase. Although prescriptions of Orlistat and Sibutramine have increased substantially since they were first introduced, the rate of growth decreased substantially in recent years until 2005, when a significant increase in the number and cost of prescriptions for orlistat occurred yet again.

Conclusions

We found a large increase in the use and costs of anti-obesity prescriptions, consistent with the increased awareness of obesity amongst health care professionals and the public. Despite this large increase, there are still no head-to-head studies at a national level that directly compare all anti-obesity medication in use in the UK.

Introduction

Obesity rates are increasing in many countries and the World Health Organisation has recognised obesity as one of the largest public health problems currently facing many societies.1 Depending on its severity, obesity significantly increases both morbidity and mortality.2 Obesity-related problems in England (based on a body mass index >30 kg/m2) cost £3.5 billion [£1 billion in treating the consequences on National Health Service (NHS) and £2.5 billion in indirect costs].3 These costs are likely to continue to increase, as the UK has one of the world's most rapidly growing obesity rates.4

The NHS is struggling to cope with the overwhelming challenge of obesity. Since 1980, the prevalence of obesity has trebled to currently affect around 22% of adults.5 Tackling this problem is worthwhile, with a 10-kg drop in weight achieving significant improvements in clinical endpoints; for example, a 20–25% decrease in all-cause mortality.6

The UK government has recently begun to prioritise the prevention and management of obesity. Obesity is now included in many of the National Service Frameworks (NSFs) in UK, which are long-term strategies for improving specific areas of care. Furthermore, the National Institute for Clinical Excellence (NICE)7 has published guidelines on orlistat, sibutramine and bariatric surgery, while the impact of obesity on society has been addressed by a parliamentary committee.3 As a result of these initiatives, awareness of bariatric (anti-obesity) pharmacotherapy has increased substantially among the health professionals and the general public. Currently, there are three approved drugs for this indication in the UK: orlistat (since 1998), sibutramine (since 2001) and rimomabant (since 2006), which reduce the absorption of fat or suppress the appetite, respectively. More than 20 new anti-obesity drug compounds are in preparation, with 2 currently in Phase III development.8

This study investigated the impact of increased awareness and prevalence of obesity on the cost and volume of prescribing for anti-obesity medication in England.

Methods

Prescription data were obtained from the Department of Health's prescription cost analysis (PCA) system, which is based on the data supplied by the Prescription Pricing Authority (PPA) for England. The PPA compiles data for the Department of Health on all the community prescriptions dispensed in England. The PCA system does not include drugs dispensed in hospitals, mental health trusts or private prescriptions. However, the vast majority of prescribing for obesity is carried out by NHS general practitioners, with relatively little done by hospital specialists. Data for sibutramine and orlistat were obtained from 1998 to 2005.

Results

Between 1998 and 2005, orlistat prescriptions rose 25-fold from 17,880 to 646,700 and total cost increased by over 35-fold (Fig. 1 and Table 1). Similarly, from 2001 to 2005, sibutramine prescriptions rose from 53,393 to 227,000 (Fig. 1 and Table 1), a 4-fold increase. Over twice as many orlistat prescriptions than sibutramine prescriptions were dispensed in 2005. Although prescriptions for orlistat and sibutramine have increased substantially since they were first introduced, the rate of growth has decreased substantially in recent years until 2005: a significant increase in the number and cost of prescriptions for orlistat then occurred in this year.

Fig. 1

The total cost and prescriptions of Orlistat and Sibutramine between 1998–2005.

Fig. 1

The total cost and prescriptions of Orlistat and Sibutramine between 1998–2005.

Table 1

The total number of prescriptions and yearly cost (in GBP) for orlistat and sibutramine in millions

Year No. of prescriptions Cost 
 Orlistat Sibutramine Orlistat Sibutramine 
1998 0.02 – 0.69 – 
1999 0.13 – 5.38 – 
2000 0.16 – 6.6 – 
2001 0.42 0.02 17.63 2.04 
2002 0.54 0.2 23.46 7.78 
2003 0.49 0.2 21.11 8.49 
2004 0.49 0.21 21.48 9.37 
2005 0.65 0.23 27.12 11.04 
Year No. of prescriptions Cost 
 Orlistat Sibutramine Orlistat Sibutramine 
1998 0.02 – 0.69 – 
1999 0.13 – 5.38 – 
2000 0.16 – 6.6 – 
2001 0.42 0.02 17.63 2.04 
2002 0.54 0.2 23.46 7.78 
2003 0.49 0.2 21.11 8.49 
2004 0.49 0.21 21.48 9.37 
2005 0.65 0.23 27.12 11.04 

Discussion

Main findings of this study

Our results highlight the combined impact of rising levels of obesity and increasing awareness of the condition on prescribing cost and volume of prescribing for anti-obesity medications. Over the last 7 years, there has been a substantial increase in the cost of anti-obesity medicines during a period in which the total NHS drug bill has increased by about 79%.9 In the future, even more resources will need to be allocated to treat obesity as its prevalence continues to increase and as newer drugs are introduced (such as rimonobant in 2006). Our findings showed that the rate of volume and cost of anti-obesity medicines increased substantially between 2001 and 2002. The introduction of the original NICE guidelines on these medications in 2001 may be responsible for this.10 In addition, the growth in the volume and cost of anti-obesity medicines decreased after 2002, only to significantly increase again for orlistat in 2005. The explanation for this temporary decrease is unclear, but it may reflect the positive effect of lifestyle interventions as this has had greater emphasis in recent years and may account for the reduced growth rate of anti-obesity medication prescribing. However, the effect of lifestyle intervention only shows modest weight loss in the long term, and the lack of evidence of other effective interventions makes it difficult to comment on this trend.11,12 Alternatively, this decrease may well just reflect unwillingness by doctors to prescribe and reduced patient compliance secondary to the sub-optimal efficacy, high relative costs and side effects.

The sudden rise in cost and volume of orlistat prescribing in 2005 is equally difficult to explain. One explanation is that it does fall in line with the reviewed NICE guidelines in 2004, which could well have increased physicians' awareness of identifying and treating obese patients. However, it is likely to be a mixture of factors, which are difficult to interpret until further data are available for subsequent years to help elaborate on this trend in detail.

What is already known about this topic

There is no clear guidance as to which medication should be used while managing the obese patient. A systematic review has not discovered any major difference in weight loss between orlistat (3.26 kg over 2 years) and sibutramine (3.4 kg over 18 months), and both have shown to be cost-effective.13 Nevertheless, orlistat currently has the larger proportion of the English market. It has been associated with a decrease in blood pressure, reduced use of concomitant type 2 diabetes medications and beneficial effects on cardiovascular risk factors.14,15 In contrast, sibutramine has the undesirable side effects of increasing systolic and diastolic blood pressure, heart rate, and low-density lipoprotein cholesterol.16 NICE guidelines on sibutramine7 advise against its use among hypertensive patients as well as compulsory blood pressure monitoring on all patients initiated on treatment. Furthermore, the cost and volume of sibutramine prescribing has seen a minimal increase in 2005 with 65% of total sibutramine prescriptions for the lower dose of 10 mg (Table 2). This accounted for just over 60% of the total cost of 10 and 15 mg doses. These differences and the familiarity of orlistat among physicians due to its earlier introduction may explain why orlistat is more popular in England. However, we have no data to support this hypothesis.

Table 2

The total number of prescriptions and yearly cost (in GBP) for sibutramine in millions for 2005

Sibutramine (mg) No. of prescriptions Cost 
10 0.15 6.77 
15 0.08 4.27 
Sibutramine (mg) No. of prescriptions Cost 
10 0.15 6.77 
15 0.08 4.27 

A cross-sectional study in the US analysed the prescribing patterns of anti-obesity drugs between 1991 and 2002 in a random sample of approximately 3500 physicians on 2 work days per quarter.17 The study was primarily undertaken to examine the change in prescription trends with the removal of fenfluramine and dexfenfluramine in 1997 due to cardiac side effects. Between 1998 and 2002, unlike the English trend, there was a decrease in the usage of anti-obesity drugs. A study in Canada (1998–2003) showed a peak in anti-obesity drugs prescriptions in 2001, which have since declined18 similar to the English trend during this time. Both papers showed orlistat was prescribed more often than sibutramine.

Strengths and limitations

Among the strengths of our study are that the NHS in the UK provides universal coverage and that most prescriptions (around 85%) are issued to patients who do not have to make any co-payments. Hence, financial barriers to medication use are substantially less than in some other countries such as the USA. The ‘single-payer’ nature of the UK NHS also means that our data are for the entire population of England and not just for a sub-sample. The main limitation of the study is that we have no data on the number of people being treated with medication for obesity, as the PCA system does not provide this information. Estimates of overweight or obesity range from 50 to 66% according to the Health Survey for England and the House of Commons Health Committee. We do not know what proportion of these people are eligible for these medications or whether they have made the initial weight loss required by guidelines to receive NHS prescriptions for orlistat or sibutramine.

Prescribing in hospitals and private clinics was not included in our data. The impact of excluding this prescribing on overall trends is likely to be very small, as the vast majority of NHS prescribing for chronic diseases is done by general practitioners; which is included in our data.

What this study adds

Our study has shown a large increase in the trends of anti-obesity prescriptions and cost, which is consistent with the increased prevalence and awareness of obesity among the health care professionals and the public. Despite this large increase, there are still no head-to-head studies at a national level that directly compare all UK anti-obesity medication. Data from this may provide better guidance and improve the targeted use of these medications in view of rising costs. Interestingly, an independent survey of UK Primary Care Trusts revealed that although 55% of respondents acknowledged obesity as one of their top priorities, only 31% of general practices have established weight management clinics19 (despite obesity being included in the new GP contract in April 2006). This highlights the importance of raising health professionals' awareness as well as applying cost-effective strategies for obese patients. Such strategies need to combine pharmacological therapy with wider public health initiatives that promote healthier diets with reduced calorific content and increased physical activity.

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