Drugs indicated for the treatment of obesity

March 2008

Introduction

The following pages contain data on the prescribing of drugs used in the treatment of obesity as defined in British National Formulary (BNF) section 4.5, in Scotland for the financial years 1998/99 to 2006/07, inclusive.  Statistics shown include prescribing volume, as measured by the number of prescribed items and defined daily dose, and the gross ingredient cost, at both Scotland and NHS Board level.

Obesity is not just a cosmetic issue.  It increases the risk of many health problems such as type 2 diabetes, heart disease, stroke, back and joint pain, high blood pressure, gall stones, fatty liver, infertility, breathlessness, osteoarthritis, sleeplessness, depression and certain cancers. 

The Department of Health and the Medical Research Council first raised it as a public health problem in a joint report in 1974 ⁽¹⁾.  Further evidence of health problems associated with obesity was produced in 1983 in a report from the Royal College of Physicians (London) ⁽²⁾ .   

The Scottish Office, Department of Health  issued a report⁽³⁾ in 1996 which identified obesity as a contributory factor in coronary heart disease.  Another report on the Scottish diet⁽⁴⁾ highlighted obesity as a growing problem of relevance to the high rates of non-insulin-dependant diabetes mellitus (NIDDM), hypertension and hypercholesterolaemia in Scotland.   

An accepted measure of obesity is the The Body Mass Index (BMI), calculated as:

BMI = Weight kg/Height m²

For example, an adult of 70 kg with a height of 175 cm has a BMI of:

70/1.75² = 22.9

The internationally accepted ranges ⁵ of BMIs are given in the following table:

In 2003 Scottish Health Survey found that 65.4% of men and 59.7% of women were either overweight or obese, with little differene in mean BMI between Scotland and England.   Obesity is rising among children too, with prevalence rates in 2 to 15 year olds rising from 14% in 1998 to 16% in 2003.  For more details please click here  . 

The main treatment of the obese individual is a suitable diet, carefully explained and fully supported, coupled with a change of lifestyle, including increased physical activity. 
 
The National Institute for Health and Clinical Excellence (NICE) in England and SIGN, The Scottish Intercollegiate Guidelines Network, have both issued guidelines on weight control and obesity in adults and children:

• SIGN - Obesity in Scotland (November. 1996)
• SIGN - Management of obesity in children and young people (April 2003)
• NICE - Obesity Guidance on the prevention, identification and management of overweight and obesity in adults and children. (December 2006)

Further information on the prevalence and treatment of obesity can be found on the following internet sites:

• National Obesity Forum
• Association for the Study of Obesity
• Health Eductaion Board for Scotland Healthy Eating

ISD is not responsible for the contents of external internet sites.

Obesity drugs

Three drugs are indicated for the treatment of obesity, as described in the  British National Formulary (BNF), issue 54, September 2007, section 4.5.

• Orlistat, (Xenical^®), was introduced in October 1998, and is an anti-obesity drug that acts on the gastro-intestinal tract, inihibiting the absorption of dietary fat. (BNF 4.5.1)
• Sibutramine, (Reductil^®), introduced in June 2001, is a centrally acting appetite suppressant that inhibits the re-uptake of noradrenaline and serotonin and is used in the adjunctive management of obesity (BNF 4.5.2).
• Rimonabant, (Acomplia^®), introduced in February 2007, is also a centrally acting appetite suppressant.  More specifically it is a cannabinoid receptor antagonist for the adjunctive management of obesity (BNF 4.5.2).

Summary

The prescribing of drugs used in the treatment of obesity in Scotland between 1998/99 and 2006/07 has been reviewed.  A summary of the findings is given below.

• A total of 104,274 items (75,039 for orlistat, 26,871 for sibutramine and 2,364 for rimonabant) were prescribed in Scotland during 2006/07, an increase of 14,404 prescriptions over the previous financial year.
• Prescribing of orlistat continues to grow at a faster rate,  14.9% in 2006/07 over the previous year, compared to sibutramine at 9.4%.
• Expenditure on "obese drugs" rose from  £4.12 to £4.89 million between 2005/06 and 2006/07.
• It is estimated that 0.214% of the population aged 12 and over, that is, around 9,500 people, make daily use of orlistat, sibutramine and/or rimonabant.  It must be emphasised that this is an estimate; the actual patient base is unknown at present.

Data Source

Practitioner Services, a division of NHS National Services Scotland, processes all NHS prescriptions for payment of pharmacies, dispensing doctors and appliance suppliers.  This gives a full record from which trends in prescribing can be investigated at a detailed level.  The data includes prescribing by GPs, nurses, dentists, pharmacists and hospitals, where the latter was dispensed in the community.  Hospital dispensed prescriptions are NOT included in the figures.  Information Services Division (ISD) cannot say what proportion of the dispensed drug is actually consumed.

A downloadable Excel file is provided that gives both the data behind the graphs and for individual drugs in BNF section 4.5.

Figure 1 shows the number of prescribed items by individual drug and in total for drugs used in the treatment of obesity in Scotland from 1998/99 to 2006/07.

Figure 1 - Number of prescribed items - Scotland 1998/99 to 2006/07

Source: Information Services Division, Healthcare Information Group

Increased awareness of the adverse health effects of obesity are demonstrated by figure 1, where the prescribing of "obesity drugs" is five times higher in 2006/07 than it was in 2000/01; the largest increase occurring between 2000/01 and 2001/02.  Orlistat is three times more likely to be prescribed than the appetite suppressant, sibutramine.

ISD cannot say how many people are receiving these drugs.  However, an approximation can be found from using the defined daily dose (DDD) as developed by the  World Health Organisation (WHO).  The DDD is defined as the "assumed average maintenance dose per day for a drug used on its main indication in adults".  DDDs are derived from the international use of the substance in question.  As British prescribing patterns may differ from the accepted international value, each DDD should be regarded as a technical value, a close approximation of an average of the actually used doses.  The DDDs are not necessarily the most frequently prescribed or used doses.

The WHO DDD for the two drugs indicated for the treatment of obesity are:

Figure 2 shows the defined daily dose given as the number of DDDs per 1,000 population per day.   This value offers an explanation of what proportion of the population may receive a certain drug treatment.  For example an estimated drug consumption of 10 DDDs per 1,000 population per day corresponds to a daily use of the drug by 1% of the population.  The population used is the mid-year estimates produced by the General Registrar Office for Scotland, but restricted to persons aged 12 and over.

Figure 2 - Number of DDDs per 1000 population (aged 12 to 90 and over) per day 1998/99 to 2006/07

Source: Information Services Division, Healthcare Information Group

The prescribing pattern exhibited in figure 2 is similar to that of figure 1, with orlistat being the most commonly prescribed drug.  The graph indicates that 0.214% of the population, that is around 9,500 people aged 12 and over, make daily use of drugs indicated for obesity.  It must be emphasised that that these figures are estimated; the actual patient base is unknown.

Figure 3 Gross ingredient cost (£) - 1998/99 to 2006/07

Source: Information Services Division, Healthcare Information Group

The total gross ingredient cost for drugs indicated for the treatment of obesity during 2006/07 was £4.89 million, up  £0.77 million from the previous year.  A general increase in prescribing of both orlistat and sibutramine, as well as the introduction of rimonabant is the reason for the increase.

The cost per defined daily dose (DDD) for 2006/07 is £1.41 or £513 per annum, up 2.6% on the previous year.  Taking the GRO mid-year population estimate for 12 years old  and over, the cost per head is calculated as £1.10 in 2006/07. 

Prescribing Statistics - NHS Boards

The following charts, for reasons of clarity, use the NHS Board cipher rather than the Board name.  Table 1 maps the cipher to the Board name.

Please not that NHS Argyll and Clyde ceased to exist as a single entity from April 2006.  Argyll and Bute was absorbed into NHS Highland and the remainder into NHS Greater Glasgow to become Greater Glasgow and Clyde.

Table 1 - NHS Board Cipher - Translation

Source: Information Services Division, Healthcare Information Group

a) Usage

The number of DDDs per 1000 population per day has been used to permit comparison in the prescribing of drugs indicated for the treatment of obesity between NHS Boards, as shown in Figure 4.

Figure 4 - DDDs per 1,000 population (Aged 12 and over) per day by NHS Board 1998/99 & 2006/07

Source: Information Services Division, Healthcare Information Group
Footnote: Data for NHS Greater Glasgow and Clyde and NHS Highland in 1998 represents the 'old'
health board structure of Greater Glasgow health board and Highland health board.  Data for
2006/07 represents the new formation of these boards, to incorporate the parts of Argyll and Clyde
from April 2006.

Three NHS Boards, Greater Glasgow and Clyde (G), Lanarkshire (L) and Western Isles (W) make the greatest use of drugs indicated for obesity.   It is estimated that 0.27% of the target population in Greater Glasgow and Clyde and Lanarkshire and 0.35% in Western Isles, that is around 2,800, 1,300 and 80 people respectively, make daily use of such drugs. This contrast with Borders (B) and Lothian (S) where only 0.08% and 0.12% of the population aged 12 and over (74 and 807 people) use either orlistat, sibutramine or rimonabant.

b) Costs

Figure 5 shows the gross ingredient cost of drugs indicated for obesity per head of population (aged 12 and over) has increased from an average of £0.04 in 1998/99 to £1.01 by 2006/07. 

Figure 5 - Gross Ingredient Cost (£) per head of population (aged 12 and over) by NHS Board
1998/99 & 2006/07

Source: Information Services Division, Healthcare Information Group
Footnote: Data for NHS Greater Glasgow and Clyde and NHS Highland in 1998 represents the 'old'
health board structure of Greater Glasgow health board and Highland health board.  Data for
2006/07 represents the new formation of these boards, to incorporate the parts of Argyll and Clyde
from April 2006.

Greater Glasgow (G), Lanarkshire (L) and Western Isles (W) have the highest cost per head at £1.36, £1.41 and £1.87 for drugs indicated for obesity, as expected from the usage data.  Ayrshire & Arran (A) and Lanarkshire (L) are the next highest at £1.19 per head of the 'target' population.  The lowest users of these drugs, Borders and Lothian, spend £0.40 and £0.60 respectively.  In total ten NHS Boards spend more than the Scottish average of £1.01 per head of population aged 12 and over.

References

1. DHSS/MRC Research on Obesity, London, HMSO 1974
2. Royal College of Physicians Obesity.  A Report by the Royal College of Physicians.  Journal of Royal College of Physicians, London 1983; 17 pp 58
3. Scottish Office Department of Health.  Coronary heart disease in Scotland.  Report of policy review.  Edinburgh:The Department of Health 1996
4. Scottish Office Home and Health Department.  The Scottish Diet.  Scotland's health: a challenge to us all.  Report of a Working Party to the Chief Medical Officer for Scotland.  Edinburgh:  The Department of Health, 1993 
5. Obesity in Scotland, Integrating Prevention with Weight Management.  Scottish Intercollegiate Guidelines Network (SIGN), Pilot Edition, November 1996, p3 

Main contact: Prescribing

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