parameters were documented (medical records): systolic blood pressure (SBP, mmHg) and diastolic blood pressure (DBP, mmHg), baseline blood glucose (mg/dl), triglycerides (mg/dl), total cholesterol (mg/dl), low density lipoprotein cholesterol (LDL-c, Friedewald in mg/dl) and high density lipoprotein cholesterol (HDLc) in mg/dl. The consumed health care resources, documented from the registries of each center, comprised the visits or appoint- ments with the Primary Care center, referrals to the reference specialists, requests for supporting complementary tests, and drug prescriptions charged to CatSalut occurring during the study period of evaluation. Visits made were deﬁned as appointments programmed between the professional team and the patient due to a health demand or problem, in the center or in the home of the patient. The design of the costs system was deﬁned taking into account the characteristics of the organization and the degree of development of the available information systems. The unit health care product serving as basis for ﬁnal calculation was the cost/patient attended during the study period. According to dependence on the volume of activity carried out, consideration was made of the ﬁxed/semi-ﬁxed costs (with imputation criteria) and the variable costs. Fixed/semi-ﬁxed costs (structure) were taken to be those relating to personnel (fees and salaries), consumer goods, and a series of expenses pertaining to external services, in accordance with the General Accounting Plan for Health Care Centers, while variable costs were taken to be those related to diagnostic or therapeutic requests, or referrals decided by the professionals of the center. The different study concepts and their economical assessment were the following: a) complementary tests, including laboratory tests (mean cost per request), conventional radiology (fee per requested test), and supporting tests (fee per requested test); b) referrals to reference specialists or to hospital centers on an ordinary or emergency basis (adjusted fee per referral); and c) prescrip- tions (medical prescriptions on an acute or chronic basis, or upon demand; public sales price per container). The fees used were obtained from analytical accountancy studies made within the organization itself, or from prices as established by CatSalut (Garcia-Cardona et al 1995; Orden de la Generalitat de Catalunya 1995). Based on the semi-ﬁxed costs, a mean cost per visit made was obtained, and a ﬁnal direct distribu- tion was carried out for each patient attended during the study period. Thus, the cost per patient (Cp) was: Cp = (mean cost per visit x number of visits [semi-ﬁxed costs]) + variable costs. As a step prior to analysis, and in particular to the information source pertaining to the case histories retrospec- tive claim database (OMIAP), a careful review was made of Neuropsychiatric Disease and Treatment 2008:4(1) Obesity and the use of antipsychotic drugs the data, in search of possible registry or coding errors. Data quality was considered adequate, and the data were obtained on a computerized basis, with due observation of the legal regulations on information conﬁdentiality. A statistical analysis was made, with calculation of the mean and standard deviation (SD), and corresponding 95% conﬁdence intervals (CI). Parametric tests (chi-square and Student t-test) were used for the relationship between vari- ables in the bivariate analysis. A logistic regression analysis (forward step procedure) was performed to correct the model, including the variables according to signiﬁcance of the results in the bivariate analysis and their clinical signiﬁcance (depen- dent variable: obesity). Comparison of ambulatory cost was made following the recommendations of Thompson and Barber (2000) based on analysis of covariance (ANCOVA) with patient sex, age, and number of co-morbidities as covari- ates (estimation of marginal means; Bonferroni correction). The SPSSWIN version 12 statistical package was used, accepting statistical signiﬁcance for p 0.05. Results Information was obtained on 42,437 patients (Table 1), with a mean age of 50.8 (18.4) years (54.5% females). The mean number of visits/year was 10.0 (9.0), with a mean number of episodes/year of 5.9 (3.8), and a mean Charlson Index of 0.4 (0.6). According to the NCEP-ATP III, 27.3% (95% CI: 26.9%–27.7%) of the population attended met criteria of obesity (BMI = 27.4 kg/m2), while 1.3% (CI: 1.2%–1.4%) were receiving treatment with APDs – fundamentally olanzapine (23.3%), risperidone (22.1%) and haloperidol (11.3%). The main reason for using antipsychotics were dis- orders of the schizophrenia spectrum [254 (46.1%)], bipolar disorders [95 (17.3%)], dementia and other cognitive deﬁcits [71 (12.8%)], restlessness [41 (7.5%)], anxiety [25 (4.5%)], organic psychoses [24 (4.4%)], and others [41 (7.4%)]. The proportion of individuals receiving treatment with APDs was signiﬁcantly greater among the obese patients: 1.8% vs. 1.1%, p 0.0001, though there were no differ- ences in proportion between conventional and atypical drugs: 48.8% vs. 51.2%, respectively, or in terms of the drug substance involved (Table 1). Obesity was associated with the majority of the general variables, co-morbidities and clinical parameters studied. A greater mean age of 57.9 (15.5) years vs. 48.2 (18.8) years, with a predominance of females 59.9% vs. 52.4%, and a greater number of visits 12.1 (9.8) vs. 9.1 (8.5) and episodes 7.0 (4.0) vs. 5.4 (3.6), respectively (p 0.001) was seen in all cases. In these patients, a larger proportion of modiﬁable cardiovascular risk antecedents 221