A quality control program to evaluate accuracy and precision of clinical chemistry determinations.

An external quality control program is described which, apart from documenting the routine performance of clinical chemistry laboratories with respect to accuracy and precision, also indicates the control efficiency of intra-laboratory quality control procedures. Participants are supplied with a large lot of stable control serum to be used in their intra-laboratory quality control program during a prolonged period of time. The statistical analysis of the submitted data consists of an analysis of variance scheme in order to separate systematic from random errors. The systematic laboratory errors are thereafter graded according to a scoring system independent of the standard deviation. The control efficiency of intra-laboratory quality control procedures is derived from a modified version of the measurability and controllability rules of Van der Grinten (1968) Stat. Neerl. 22, 43--63). Application of these rules in clinical chemistry laboratories is a first step towards a dynamic system of process deviation control. Merits of such an approach are discussed. Principles of the analysis of variance technique are dealt with. A graphical procedure to display its results is shown. Testing procedures to justify application of the analysis of variance technique are discussed and several features are illustrated.

Dynamic deviation control in clinical chemistry laboratories based on the time variant behaviour of analytical processes.

Based on the time variant behaviour of analytical processes, a dynamic system of deviation control is discussed. Originating from industrial process control, measurability and controllability rules as measures of the optimum reconstructing and controlling efficiency of quality control systems are introduced. It is seen that when trying to reconstruct and control and analytical process, properties of the process and characteristics of the control system need to be taken into consideration. Application of these rules offers the possibility of investigating the effect of actions aimed at improving the performance of a controlling system, but also indicates if a certain precision requirement can be achieved with less effort and expense. An example illustrates the time variant behaviour of an analytical process used for urea determination in a clinical chemistry laboratory. It shows the applicability of measurability and controllability rules, with the emphasis on the measuring or reconstructing efficiency of the controlling system used in that laboratory for the surveillance of the urea determination.

Modern life' in the epidemiology of inflammatory bowel disease: a case-control study with special emphasis on nutritional factors.

OBJECTIVE: The rising incidence of inflammatory bowel disease (IBD) since the Second World War coincides with profound changes of the dietary pattern. The aim of the study was to investigate the possible pathogenic role of some characteristic 'modern life' dietary factors in IBD. DESIGN: Case-control, studying risk factors in recently diagnosed cases, 290 with Crohn's disease and 398 with ulcerative colitis, compared with 616 population controls. Smoking, age, gender and education were taken into account by using logistic regression analysis. SETTING: Hospital cases and population controls. INTERVENTIONS: Questionnaires. MAIN OUTCOME MEASURES: Logistic regression-derived odds ratios. RESULTS: A positive association with cola drinks [OR: 2.2 (95% CI 1.5-3.1)], chewing gum [OR: 1.5 (95% CI: 1.1-2.1)] and chocolate consumption [OR: 2.5 (95% CI: 1.8-3.5)] and a negative association with citrus fruit consumption [OR: 0.5 (95% CI 0.3-0.7)] and the development of Crohn's disease were found. Consumption of cola drinks [OR: 1.6 (95% CI 1.1-2.3)] and chocolate consumption [OR: 2.5 (95% CI 1.8-3.5)] were positively associated with developing ulcerative colitis. There was a negative association between the intake of citrus fruits [OR: 0.5 (95% CI 0.4-0.8)] and 'having a stuffed pet' for a period longer than 5 years [OR: 0.6 (95% CI 0.4-0.9)] and developing the disorder. No association with the frequency of tooth brushing and developing IBD was found. CONCLUSION: All the nutritional items mentioned may be true risk factors or they just might be the expression of a modern life-style also involving other risk factors for the development of IBD which at the present are still unknown.

Computerized health information in The Netherlands: a registration network of family practices.

A registration network of family practices (Registratienet Huisartspraktijken) has recently been established in the Netherlands. Forty two general practitioners in 15 practices, with a patient population of 80,000 people, are using a general practice health information system to establish a central computerized anonymous database containing certain patient characteristics and all relevant health problems. By September 1990 patient characteristics and problem lists for 32,972 patients had been entered and a total of 94,476 health problems had been identified. The database has been set up primarily as a sampling frame, allowing researchers to identify patients with particular health problems. The database can also provide descriptive data on prevalence and incidence rates, fulfil a monitoring function and provide data for practice audit, medical education and health management.

Unlocking patients' records in general practice for research, medical education and quality assurance: the Registration Network Family Practices.

General practitioners (GPs) possess a wealth of information on the health of their patients. Hence, they are in a unique position to gather information for research, education or management. The chief goal of the Registration Network Family Practices is to establish a computerized database containing certain patient characteristics and all relevant health problems excluding minor, temporary illnesses. The database can be seen as a dynamic population sampling frame of chronic and/or severe morbidity, also including risk factors and psychosocial problems. The best way to make use of the Registration Network Family Practices is by researchers identifying and sampling patients with particular health problems. The database contained patient characteristics and problemlists of 61,887 persons, on September 1, 1995. At that time 214,389 health problems had been entered in the database. The database is increasingly being used as a source of information for studies by researchers and students. Researchers find the database a useful tool, but they have to keep in mind that data on the process of care are not directly available. Furthermore, there is a limit to the number of studies which can be performed in the network practices, due to time limitations and the burden on the doctors and patients.

High incidence of inflammatory bowel disease in The Netherlands: results of a prospective study. The South Limburg IBD Study Group.

PURPOSE: To gain recent epidemiologic information about inflammatory bowel disease in The Netherlands, a prospective study over four years (1991-1995) was performed. METHODS: The incidence of inflammatory bowel disease and its subgroups was examined using standardized reports of newly diagnosed patients. A separate study compared the Inflammatory Bowel Disease Registration and computerized diagnostic files of a subgroup of general practitioners with the aim of estimating completeness of case ascertainment. RESULTS: The following mean incidence rates (per 100,000 inhabitants and year) were found: 6.9 (95 percent confidence interval, 5.9-7.9) for Crohn's disease, 10 (95 percent confidence interval, 8.7-11.2) for ulcerative colitis (23 percent of these with ulcerative proctitis), and 1.1 (95 percent confidence interval, 0.7-1.5) for indeterminate colitis. In the age category 20 to 29 years, the incidence rate of Crohn's disease with small-bowel involvement was higher in females than in males. In extended ulcerative colitis, a male preponderance was observed in the older age groups. Estimated case ascertainment was 78 percent. CONCLUSIONS: Compared with recent studies in neighboring countries, the observed age and gender standardized incidence rates are high in the south of The Netherlands. Completeness of case ascertainment might have contributed to this observation; however, case ascertainment was low in ulcerative proctitis. In the study area, differences in age and gender standardized incidence rates and in disease localizations could be compatible with an influence of environmental risk factors.

Disease outcome in inflammatory bowel disease: mortality, morbidity and therapeutic management of a 796-person inception cohort in the European Collaborative Study on Inflammatory Bowel Disease (EC-IBD).

BACKGROUND: The course of inflammatory bowel diseases (IBD) has mainly been studied using different methods in single patient cohorts. The aim of the present study was to assess clinical aspects of disease outcome in a population-based cohort of IBD patients over a 4-year period in multiple centres across Europe. METHODS: A total of 796 patients with IBD diagnosed in 10 centres between October 1991 and October 1993, registered at the EC IBD study centre (98% of the original cohort), participated in the study. Investigators filled out a standard follow-up form containing questions on the method of follow-up, vital status of the patient, change in diagnosis, extraintestinal manifestations, medical and surgical treatment, and physician's global assessment of disease activity. RESULTS: Complete relief of the complaints was reported in 255 (48%) patients with ulcerative colitis (UC), 9 (50%) with indeterminate colitis (IC), but only in 87 (35%) of patients with Crohn disease (CD). Improvement was reported in 195 (37%) patients with UC, 113 (45%) with CD and 6 (33%) with IC. During the 4-year follow-up period, 23 patients died (14 UC, 8 CD. and 1 IC). The mean age at death was 69.3 years (s, 14.9 years). The deaths of three patients were recorded as directly due to IBD. CONCLUSIONS: With the present approach to therapeutic management the short-term outcome of patients with IBD seems to be favourable in 10 medical centres in the north and south of Europe. However, more detailed studies including both objective and subjective measures are necessary.