French National Health Insurance System Research Articles

A time series study of gastroenteritis and tap water quality in the Nantes area, France, 2002–2007

In the Nantes area, 410,000 inhabitants are supplied with water pumped from the Loire River. The treatment of this water is carried out through a process of complete clarification and disinfection. During the study period (2002-07), the quality of drinking water complied with European microbial standards and mean turbidity in finished water was 0.05 NTU (nephelometric turbidity units). We aimed to characterize the link between produced water turbidity and other operational data and the incidence of acute gastroenteritis (AGE) in the Nantes area. The daily number of medical prescriptions for AGE was drawn from the French national health insurance system's drug reimbursement data. We modeled this time series using Poisson regression within the framework of a Generalized Additive Model. We showed that an interquartile range turbidity degradation (0.042-0.056 NTU) was connected to a 4.2% (CI95=(1.5%; 6.9%)) increase in the risk of AGE in children and a 2.9% (CI95=(0.5%; 5.4%)) increase in adults. The slope of the turbidity risk function was higher during both high- and low-water conditions of the river. High values of daily flow of produced water were also associated with higher endemic levels of AGE.

Elderly patients with colorectal cancer: Treatment modalities and survival in France from the ThInDiT observational cohort study.

e14065 Background: More than 40% of the colorectal cancers (CRC) occur in elderly patients. Epidemiological data suggests that treatment modalities in this population differ from younger patients. We analysed the management of CRC patients in the real life in France using the French national health insurance system database. Methods: ThInDiT (Therapeutic Innovations in Digestive Tumors) is an observational cohort of 31 665 incident CRC diagnosed between April 1st and December 31th 2009 and registered in the French national health insurance system database. Using this cohort, we compared disease characteristics and treatment modalities within the first year of diagnosis between elderly (age >= 75) and younger patients (<75 years). Results: Elderly patients (pts) represented 42% (13 255/31 665) of the cases. They had more frequently an advanced stage at diagnosis (synchronous metastases: 20.5% vs 19.5% p=0.02, occlusion: 17% vs 11% p<0.0001). Pts with a localised disease (n=25 353): Surgery was performed in more than 80% of the cases in both age groups, delay between diagnosis and surgery was significantly shorter in elderly pts (8 vs 23 days p<0.0001) suggesting that emergency surgery was more frequent in this age group. An adjuvant chemotherapy (CT) was less frequently prescribed among elderly pts (15% vs 29% p<0.0001), 50% of the elderly received a 5FU alone whereas 79% of the younger pts had an oxaliplatin-based adjuvant CT. Pts with synchronous metastases (n= 6 312): Administration of palliative CT in elderly vs younger pts: 48% vs 85%, p<0.0001. CT regimen: LV5FU2 or capecitabine (30% vs 10%), Oxaliplatin-5FU (30% vs 34%), CT + bevacizumab (20% vs 35%) respectively. Elderly pts received less frequently a second or third line of CT than younger pts. Median overall survival was 8.4 months in elderly and 22.1 months in younger pts. Conclusions: Elderly patients represent more than 40% of incident CRC in France, they have a more advanced disease at diagnosis than younger pts. Treatment modalities are different among elderly and younger pts. Elderly pts have a worse prognosis than younger pts.

Early discontinuation of tamoxifen intake in younger women with breast cancer: Is it time to rethink the way it is prescribed?

BackgroundTamoxifen is the main recommended adjuvant hormonal treatment for premenopausal women with hormone-responsive early breast cancer. Little data is available on compliance and persistence to tamoxifen intake in younger women. MethodsUsing the French National Health Insurance System database, we constituted a cohort of 288 women who were diagnosed with breast cancer and received at least one supply of tamoxifen for breast cancer between September 2005 and July 2011. Medical records and mailed questionnaires provided complementary sources of data. Time to treatment discontinuation and associated predictors were studied using techniques for censored data. ResultsAmong women who received a prescription of tamoxifen, 6.1% (16) did not fill any prescription. After 2years of tamoxifen intake, 29.7% (95%confidence interval (CI) 24.1–36.4) had discontinued their treatment; after 3years this percentage increased to 39.5% (95%CI 32.9–47.0). The risk of treatment discontinuation rose sharply during the 1st year of treatment and remained approximately constant in the second year. After multivariate adjustment, tamoxifen discontinuation increased significantly with low social support (Hazard Ratio (HR)=2.1; 95%CI 1.2–3.4), and self-reporting of non-compliance behaviour (HR=2.2; 95%CI 1.3–3.7). ConclusionThe consequences of high treatment discontinuation rates in younger women with long potential life expectancy may be significant. There is an urgent need to acknowledge and tackle compliance issues in the field of oncology, unless we are willing to accept inefficient prescriptions of efficacious drugs.

First-line treatment of advanced colorectal cancer with bevacizumab in France: The ThInDiT observational cohort study.

655 Background: ThInDiT (Therapeutic Innovations in Digestive Tumors) is an ambispective observational cohort study based on the database of the French national health insurance system. Using this database, we analysed the use of bevacizumab in the front-line treatment of metastatic colorectal cancer. Methods: Patients and treatment characteristics were collected for 4 273 incident cases of colorectal cancer with synchronous metastases diagnosed between April 1st and September 30th 2009. A logistic regression was used to identify factors predictive of non-prescription of bevacizumab among patients receiving chemotherapy within the first three months. Results: 2 757 (64.5%) received chemotherapy, in combination with bevacizumab in 827 patients (30% of the treated patients). Median age was 64 years in the bevacizumab group against 70 years in the no bevacizumab group (p<0.0001). Major factors significantly associated with the non-prescription of bevacizumab in multivariate analysis were: age ≥ 75 years (OR= 2.47, IC95% 1.9-3.1), unresected primary tumour (OR=1.44, IC95% 1.2-1.8), rectal site (OR= 1.37, IC95% 1.1-1.8), peritoneal carcinosis (OR=1.37, IC95% 1.1-1.7), radiotherapy within the last month (OR=3.59, IC95% 2.1-6.1), arterial (OR= 1.72, IC95% 1.1-2.6) or venous (OR=2.04, IC95% 1.3-3.1) thromboembolic event within 6 months, arterial hypertension (OR=1.37, IC95% 1.1-1.7), wound (OR=3.35, IC95% 1.3-8.7), chronic bronchopneumopathy (OR=1.66, IC95%: 1.0-2.7), nephropathy (OR=2.69, IC95% 1.5-4.7). Brain metastasis and colonic endoprothesis were not associated. 1-year overall survival rate was 81% in the bevacizumab group and 76% in the no bevacizumab group. Conclusions: Based on the database of the national health insurance system, this analysis reports data on the use of chemotherapy in combination with bevacizumab in the French population, reflecting the real life practice among non-selected patients. About 2/3 of the patients with synchronous metastatic colorectal cancer are treated with chemotherapy, in combination with bevacizumab in 30% of the cases. Patients receiving bevacizumab are younger with less comorbidities.

P419 Isotretinoin use and risk of inflammatory bowel disease: A case control study from the French national health insurance system

P419 Isotretinoin use and risk of inflammatory bowel disease: A case control study from the French national health insurance system

Serum sex steroids measured in middle-aged European and African–Caribbean men by gas chromatography–mass spectrometry

Differences in circulating steroid hormone levels have been hypothesized to explain ethnic differences in steroid-related diseases. The aim of this study was to determine the serum levels of a wide panel of steroid hormones, both androgens and estrogens, in healthy middle-aged African-Caribbean and European men. Serum steroid hormone levels were determined in men participating in a systematic public health study funded by the French National Health Insurance system. Blood was collected in the morning from 304 healthy African-Caribbean and European men aged between 40 and 69 years. Serum steroids were measured by mass spectrometry-gas chromatography, except for DHEAS and sex hormone-binding globulin, which were determined by RIA. Data were analyzed in 10-year age intervals by analysis of covariance, with adjustment for age, body mass index, waist-to-hip ratio, tobacco and alcohol consumption, and season of sampling. Compared with Europeans, African-Caribbean men presented significantly higher serum levels of measured bioavailable testosterone, 4-androstenedione (4-dione), and estrone (E1) regardless of the age group, of 5-androstenediol (5-diol) in those aged 40-49 and 50-59 years, and of testosterone (TT) and dihydrotestosterone in those aged 40-49 years. In contrast, European men aged 40-69 years showed significantly higher serum levels of DHEA and DHEAS. Significant differences in serum steroid hormone levels were observed in middle-aged African-Caribbean and European men. Whether such differences could contribute to ethnic differences in disease risk in adult men remains to be investigated. Some steroids, such as bioavailable TT, 4-dione, 5-diol, and E1, deserve particular attention.

Adherence with statins in a real-life setting is better when associated cardiovascular risk factors increase: a cohort study

BackgroundWhile the factors for poor adherence for treatment with statins have been highlighted, the impact of their combination on adherence is not clear.AimsTo estimate adherence for statins and whether it differs according to the number of cardiovascular risk factors.MethodsA cohort study was conducted using data from the main French national health insurance system reimbursement database. Newly treated patients with statins between September 1 and December 31, 2004 were included. Patients were followed up 15 months. The cohort was split into three groups according to their number of additional cardiovascular risk factors that included age and gender, diabetes mellitus and cardiovascular disease (using co-medications as a proxy). Adherence was assessed for each group by using four parameters: (i) proportion of days covered by statins, (ii) regularity of the treatment over time, (iii) persistence, and (iv) the refill delay.Results16,397 newly treated patients were identified. Of these statin users, 21.7% did not have additional cardiovascular risk factors. Thirty-one percent had two cardiovascular risk factors and 47% had at least three risk factors. All the parameters showed a sub-optimal adherence whatever the group: days covered ranged from 56% to 72%, regularity ranged from 23% to 33% and persistence ranged from 44% to 59%, but adherence was better for those with a higher number of cardiovascular risk factors.ConclusionsThe results confirm that long-term drug treatments are a difficult challenge, particularly in patients at lower risk and invite to the development of therapeutic education.

Mortality of Inflammatory Bowel Disease (IBD): A Study of Data From the French National Health Insurance System in 2008

Mortality of Inflammatory Bowel Disease (IBD): A Study of Data From the French National Health Insurance System in 2008

Assurance maladie. Un état des lieux

An audit of the French national health insurance system would be justified by economic considerations alone, but this would risk overlooking the notions of solidarity and freedom to which the French are rightly attached. European comparisons suggest, however, that our system could be made more efficient without undermining public health. The national health insurance system allows each member of the population to receive high-quality medical care. Practitioners have near-total freedom of prescription and practice. Medical care contributes to the ongoing increase in life expectancy, which is currently 73 years and second only to Japan. Healthcare is also a source of a million jobs. Macro-economic spending controls have failed, owing to medical progress and population aging, and also to medical consumerism favored by an unprecedented range of examinations and treatments, the increasing reimbursement of medical care, and the extension of direct payment by the insurer. Many ineffective measures have been implemented, such as tarification according to activity, and hospital certification. Health spending is also increased unnecessarily by bureaucratisation of healthcare spending and the transfer of professionals to posts for which they are not qualified. Some controversial medical prescriptions are not adequately controlled by the health service. Many reforms are based on over-optimistic economic predictions that fail to take related overheads into account. Lobbying by special interests groups undermines reform and the public interest. Too many independent administrative bodies have been created, and many are less efficient than the public structures they replaced. In sum, the French national health insurance system has become less and less efficient over the years.

How reimbursement databases can be used to support drug utilisation studies: example using the main French national health insurance system database

Reimbursement databases are potentially invaluable tools to develop and conduct pharmacoepidemiological studies on drug use. However, two types of factors that may influence the performance of a database can be distinguished: firstly, factors related to the constitution of the database, and secondly, factors related to the data. For the latter, we think that two are important: the presence of the drug in the database and the capacity to capture real-life use, both of which are influenced by the marketing status (e.g., OTC) and whether reimbursement is possible. To illustrate and discuss to what extent reimbursement databases are relevant tools to conduct drug utilization studies with regard to the data on drugs. In order to illustrate the reliability of data in reimbursement databases, data from the main French national health insurance database (55 million individuals) were compared to national drug sales in France (units) during the same year. Depending on the ATC class, the capture in the database of drugs actually sold ranged from 32 to 81%. Capture of classes of drugs in the database may be explained by the specific characteristics of the French health insurance system (reimbursable drugs, OTC market share). These characteristics influence the studies that can be performed both in terms of the topic but also the methodology. This problem probably exists for the other reimbursement databases used worldwide. Studies should be designed according to the strengths and weaknesses of reimbursement databases that were not originally developed for pharmacoepidemiology.

Comparison of health insurance claims and patient interviews in assessing drug use: data from the Three‐City (3C) Study

Precise determination of drug exposure is fundamental in pharmacoepidemiology. Drug exposure is often presumed from health insurance claims but this may not correspond exactly to what subjects actually take. This study was designed to investigate French reimbursement databases in assessing drug use. Between 1999 and 2001, 9294 subjects were included in the Three-City (3C) Study, a French cohort studying the relationship between vascular risk factors and dementia. Of these, 4112 subjects had data available from both clinical interviews and the reimbursement databases of the French national health insurance system. Agreement between drugs reported as used at interview and drugs reimbursed during the previous 30 or 60 days was measured with kappa coefficients. Using calculations of sensitivity (Se), specificity (Sp), positive predictive values (PPVs) and negative predictive values (NPVs), the validity of reimbursement data for the 30 or 60 days preceding the interview was investigated taking drugs reported at interview as the 'gold standard'. Declared drug use at interview was less well predicted by 30-day than by 60-day reimbursement data. Agreement between reimbursement data and interviews as well as validity of reimbursement data with reference to interviews were substantial for drugs used in cardiovascular diseases, diabetes, rheumatic disorders or neuropsychiatric conditions and were poor for laxatives, vitamins, vasculoprotectives, first and second line analgesics, anti-infective products or dermatologicals. Reimbursement data with an appropriate time frame and interviews estimate exposure to chronically used drugs similarly. Self-medication was better described with interviews whereas reimbursement data seem more useful for drugs used topically or intermittently.

Reimbursement of malaria chemoprophylaxis for travellers from Europe to Sub-Saharan Africa: Cost-effectiveness analysis from the perspective of the French national health insurance system

Among Western countries, France has the highest incidence of imported malaria cases, mostly from travellers visiting Sub-Saharan Africa (SSA). Despite related high costs of imported malaria assumed by the public French national health insurance system (FHS), the latter does not reimburse travellers for malaria chemoprophylaxis (MC). This study aims to analyzes, from the FHS perspective, the cost-effectiveness of a 65% reimbursement of MC costs (MC 65%) for French resident travellers, under the assumption that this reimbursement would lead to increased recourse to MC. For that purpose, a decision tree model was developed with variables obtained from the literature, including incidence of malaria among travellers in the absence of MC, probabilities of recourse to MC, MC effectiveness and costs and medical expenses for a case of imported malaria. Data analysis of 1,434,675 travellers to SSA in 2005 estimated, for MC 65% vs. MC 0%, incidence of malaria cases to be 3836 malaria cases (21 deaths)/year vs. 6321 cases (34 deaths)/year, respectively, and cost of Euro 47,071,687/year vs. Euro 17,416,955/year. Incremental cost of MC 65% related to MC 0% was Euro 11,933 per malaria case prevented and Euro 2,281,133 per malaria-related death prevented. Results generated by this model, which can be adapted for other European countries, should be an incentive for the FHS to favourably consider MC 65% for French residents travelling to SSA.

French medical practice in type 2 diabetes: The need for better control of cardiovascular risk factors

Aims In type 2 diabetes (T2D), to describe treatments to prevent cardiovascular disease, to compare current practice to French guidelines, and to identify factors associated with recommended treatments. Methods In the Échantillon National Témoin Représentatif des Personnes Diabétiques (ENTRED) study, 10,000 adults treated for diabetes (any type) were randomly selected from the French National Health Insurance System database. Deliveries during the last quarter of 2001 of treatments to prevent cardiovascular disease were extracted. The questionnaires were mailed to these people and their care providers. Final populations included 3324 people with T2D and their 1553 care providers. Results Overall, 18% reported coronary heart disease (CHD) and 44% others were classified as having a high cardiovascular risk; 68% received one or more antihypertensive treatment: ACE inhibitor/angiotensin receptor blocker (ARB), 44%; diuretic, 35%; calcium channel blocker, 25%; beta-blocker, 24%. Among those receiving antihypertensive treatment, 59% had blood pressure greater than 130/80 mm Hg. Overall, 42% received a hypolipidaemic treatment: statin, 25%; fibrate, 18%. About half the people with a high cardiovascular risk had LDL cholesterol greater than 1 g/L, but only 32% were given a statin. Among people with an abnormal albumin/creatinine ratio (11%), 59% received an ACE inhibitor/ARB. Among those with CHD, 35% received the two treatments recommended in 1999 (beta-blockers and antiplatelet agents); in multivariate analyses, this two-treatment delivery was positively associated with male gender, self-reported hypertension and consulting a cardiologist. Conclusion Cardiovascular risk profiles reported by providers in T2D people are high. Despite recent progress, there is a need for major improvement in practices intended to prevent cardiovascular disease in these people, especially in those at greatest CHD risk.

Study of the use of a spironolactone and angiotensin‐converting enzyme inhibitor combination: a population‐based analysis

To analyse the conditions of use of the drug combination in outpatients. The first section consisted of a population-based analysis using computerized records from the French national health insurance system. The study population consisted of adult patients, receiving long-term treatment with spironolactone (SPIR) and angiotensin-converting enzyme inhibitor (ACEI). For each patient, the reimbursement of serum potassium and creatinine determinations was searched for in the database during the 6-month period preceding the date of the last dispensation. The second section comprised a written questionnaire on use practises, sent to practitioners who prescribed the drug combination to randomly selected patients. Analysis of the answers to the questionnaire made it necessary to develop a reference system. In the third section, procedure one was repeated at a later stage, following an information campaign, in order to measure its impact. The exhaustive population under procedure 1 consisted of 3620 patients (71 +/- 11 years). During the 6 months prior to the index date, 51% of patients underwent at least one determination of both serum potassium and serum creatinine. The randomised population under procedure two consisted of 441 patients (70 +/- 13 years) and their 375 practitioners. When compared with the reference system, SPIR-ACEI was used for the recommended indications, at the appropriate SPIR-ACEI dosages, and under minimal monitoring of biological parameters in only 65 patients (15%). After the information campaign, results were disappointing because only 55% of patients underwent the minimal laboratory monitoring. The use of the drug combination in general practice was mainly inappropriate.

Cost-of-illness study of severe haemophilia A and B in five French haemophilia treatment centres

The aim of this study was to assess the consumption of anti-haemophilic drugs by adults and children with severe haemophilia A or B (residual activity of FVIII or FIX < or =2%) and to quantify the average direct medical costs. A retrospective multicentre cost-of-illness study from the perspective of French national health insurance system. The costs include only the use of clotting factors. Consumption was expressed in UI/kg/year and costs in euros/kg/year. From January 1, 2001 to December 31, 2002, data from 81 adults and 30 children with severe haemophilia A (n = 92) or B (n = 19) and included in the "SNH" were collected and analysed. A coagulation factor inhibitor was present in 10 patients (9%). Four of them were high responders. Mean age and body weight were respectively 28 +/- 17 years and 58 +/- 24 kg. Except for one adult patient, all (99%) had outpatient treatment, 44 patients (40%) were hospitalized and treated by recombinant or/and plasma-derived FVIII or FIX or/and rFVIIa. Overall median annual consumption of anti-haemophilic drugs per patient was estimated at 1,333 UI/kg, with a median cost-of-illness of 1,156 euros/kg. Patients with severe haemophilia B consumed more than patients with severe haemophilia A, though not significantly (P = 0.096), with a median of 2,167 vs. 1,100 UI/kg/year and a median cost of 1,760 vs. 917 euros/kg/year (P = 0.13). Children consumed respectively more than adults (P = 0.008), with a median of 3,204 vs. 1,106 UI/kg/year and a median cost of 2,614 vs. 913 euros/kg/year (P = 0.012). The median cost for patients with an inhibitor was 3,291 euros/kg/year, approximately threefold higher than that of patients without an inhibitor (926 euros/kg/year) (P = 0.022). It suggests a higher consumption and cost of anti-haemophilic drugs among children when compared to adults. Haemophilia B patients did not consume significantly more than haemophilia A patients, whereas the consumption and cost for patients with or without inhibitors differed significantly.

Chronic Diseases in Self-Employed French Workers

The objective of this study was to evaluate occupations associated with a high risk of specific chronic diseases in self-employed workers. For each occupational category and gender, the observed and expected numbers of prevalent cases for each chronic disease leading to exemption from copayments by the French National Health Insurance System in 2001 were compared using the age-specific self-employed population rates as a reference. Dramatic discrepancies were observed depending on occupational categories, specifically for diabetes mellitus, cardiovascular diseases, mental health disorders, chronic respiratory insufficiency, severe liver disorders, and connective tissue diseases. Based on this extremely large dataset, several known associations between occupations and specific diseases were confirmed; other potential associations observed require future investigation.

Estimated number of women likely to benefit from bone mineral density measurement in France

Objectives. – To determine the number of women in France at least 50 years of age with risk factors for osteoporosis likely to lead to bone mineral density measurement, an investigation reimbursed by the French national health insurance system in patients at risk for osteoporosis. The study was commissioned by the French health authorities. Materials and methods. – Risk factors for osteoporosis were defined as recommended by the French Agency for Accreditation and Evaluation in Health (ANAES) in 2001. The study data were from nine cohort studies done in France and from the National Health Insurance Agency for the Rhône-Alpes region of France. Risk factor prevalences in France were standardized by extrapolation according to the age distribution in France. Results. – Overall, data were collected in 123 986 women aged 50 years or older. From these data, risk factor estimates were as follows: menopause before 40 years of age, 1.5 million women; body mass index (BMI) lower than 19 kg/m 2, nearly 700 000; history of fracture, more than 2 million; history of femoral neck fracture in the mother, more than 1 million; history of health problems potentially responsible for osteoporosis, 400 000; and history of long-term glucocorticoid therapy, 612 000. In all, 3186 318 (30%) women were estimated to have at least one risk factor and 785 512 (7.5%) at least two risk factors. Conclusions. – Although our study sample was not representative of the population residing in France, the large sample size and diversity of data sources support the validity of our estimate of the prevalence of risk factors for osteoporosis in postmenopausal women living in France.

Estimation du nombre de femmes françaises à risque d’ostéoporose susceptibles de bénéficier d’une ostéodensitométrie

Objectives. – To determine the number of women in France at least 50 years of age with risk factors for osteoporosis likely to lead to bone mineral density measurement, an investigation reimbursed by the French national health insurance system in patients at risk for osteoporosis. The study was commissioned by the French health authorities. Material and methods. – Risk factors for osteoporosis were defined as recommended by the French Agency for Accreditation and Evaluation in Health (Anaes) in 2001. The study data were from nine cohort studies done in France and from the national health insurance agency for the Rhône-Alpes region of France. Risk factor prevalences in France were standardized by extrapolation according to the age distribution in France. Results. – Overall, data were collected in 123,986 women aged 50 years or older. From these data, risk factor estimates were as follows: menopause before 40 years of age, 1.5 millions women; body mass index (BMI) lower than 19 kg/m 2, nearly 700,000; history of fracture, more than 2 millions; history of femoral neck fracture in the mother, more than 1 million; history of health problems potentially responsible for osteoporosis, 400,000; and history of long-term glucocorticoid therapy, 612,000. In all, 3,186,318 (30%) women were estimated to have at least one risk factor and 785,512 (7.5%) at least two risk factors. Conclusions. – Although our study sample was not representative of the population residing in France, the large sample size and diversity of data sources support the validity of our estimate of the prevalence of risk factors for osteoporosis in postmenopausal women living in France.

Cost-effectiveness evaluation of vaccination against Haemophilus influenzae invasive diseases in France

A cost-effectiveness analysis of a vaccination program against Haemophilus influenzae type b (Hib) was conducted using French epidemiological data. The vaccine would be added as a fifth valence to the tetravalent vaccines (DTCP) widely used in France. The permanent sequelae of the Hib invasive diseases which might be avoided by vaccination were weighted to determine Quality Adjusted Life Years gained. In a stable French population of 3746000 children aged <5 years old (1990), and for a followup period of ten years, the cost-effectiveness ratio of such a program for the French national health insurance system would equal 54084 FF per year of life added or 34050 FF per QALY. The net cost of the program during that period would be 1.02 billion FF for the French national health insurance system and 920 million FF for patients' families. Comparison of these projections with available information supports, a posteriori, the decision of the French government to authorize the licensing of the pentavalent vaccine.

The economic consequences of NSAID-induced gastropathy in the United Kingdom and commentary on the article by G. de Pouvourville.

The iatrogenic cost factor of treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) is defined as the increase in cost resulting from NSAID-induced gastroduodenal ulcers. The iatrogenic cost factor of NSAIDs for the National Health Service (NHS) in the United Kingdom was calculated using the model of de Pouvourville (1992). The cost factor is defined as the ratio of the shadow price of the NSAID to the NHS price. The shadow price is calculated from the incidence of NSAID-induced gastroduodenal ulcers and the costs of treating them and the price of the drugs. The NHS iatrogenic cost factors of 10 NSAIDs were similar to those calculated by de Pouvourville for the French national health insurance system, Assurance-Maladie, and ranged from 1.08 for diclofenac/misoprostol to 2.38 for ibuprofen.