Influence of body mass index on prescribing costs and potential cost savings of a weight management programme in primary care

• Published in: Journal of health services research & policy 2008-07, Vol.13 (3), p.158-166
• Main Author: Counterweight project Team
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Anti-Obesity Agents - economics; Anti-Obesity Agents - therapeutic use; Body Mass Index; Cost of Illness; Cost Savings - statistics & numerical data; Costs; Drug Costs - statistics & numerical data; Drug Prescriptions - economics; Drug Utilization Review; Female; Health administration; Humans; Male; Medical Audit; Middle Aged; Models, Econometric; Obesity - complications; Obesity - drug therapy; Obesity - economics; Obesity - prevention & control; Original research; Outcome Assessment (Health Care); Prescriptions; Primary Health Care - economics; Primary Health Care - methods; Primary Health Care - standards; Regression Analysis; Savings; United Kingdom; Weight
• ISSN: 1355-8196; 1758-1060
• DOI: 10.1258/jhsrp.2008.007140

Objectives: Prescribed medications represent a high and increasing proportion of UK health care funds. Our aim was to quantify the influence of body mass index (BMI) on prescribing costs, and then the potential savings attached to implementing a weight management intervention. Methods: Paper and computer-based medical records were reviewed for all drug prescriptions over an 18-month period for 3400 randomly selected adult patients (18–75 years) stratified by BMI, from 23 primary care practices in seven UK regions. Drug costs from the British National Formulary at the time of the review were used. Multivariate regression analysis was applied to estimate the cost for all drugs and the 'top ten' drugs at each BMI point. This allowed the total and attributable prescribing costs to be estimated at any BMI. Weight loss outcomes achieved in a weight management programme (Counterweight) were used to model potential effects of weight change on drug costs. Anticipated savings were then compared with the cost programme delivery. Analysis was carried out on patients with follow-up data at 12 and 24 months as well as on an intention-to-treat basis. Outcomes from Counterweight were based on the observed lost to follow-up rate of 50%, and the assumption that those patients would continue a generally observed weight gain of 1 kg per year from baseline. Results: The minimum annual cost of all drug prescriptions at BMI 20 kg/m2 was £50.71 for men and £62.59 for women. Costs were greater by £5.27 (men) and £4.20 (women) for each unit increase in BMI, to a BMI of 25 (men £77.04, women £78.91), then by £7.78 and £5.53, respectively, to BMI 30 (men £115.93 women £111.23), then by £8.27 and £4.95 to BMI 40 (men £198.66, women £160.73). The relationship between increasing BMI and costs for the top ten drugs was more pronounced. Minimum costs were at a BMI of 20 (men £8.45, women £7.80), substantially greater at BMI 30 (men £23.98, women £16.72) and highest at BMI 40 (men £63.59, women £27.16). Attributable cost of overweight and obesity accounted for 23% of spending on all drugs with 16% attributable to obesity. The cost of the programme was estimated to be approximately £60 per patient entered. Modelling weight reductions achieved by the Counterweight weight management programme would potentially reduce prescribing costs by £6.35 (men) and £3.75 (women) or around 8% of programme costs at one year, and by £12.58 and £8.70, respectively, or 18% of programme costs after two years o