[Linkage of statutory health insurance data with those of a hospital information system: feasible, but also "useful"?]. / Verknüpfung von Routinedaten der Gesetzlichen Krankenversicherung mit Daten eines Krankenhausinformationssystems: Machbar, aber auch "nützlich"?

AIM: Administrative data are increasingly being linked with other data sources for research purposes in the field of epidemiology and health services research abroad. In Germany, the direct linkage of routine data of statutory health insurance (SHI) providers with other data sources is complicated due to strict data protection requirements. The aim of this analysis was to evaluate an indirect linkage of SHI routine data with data of a hospital information system (HIS). METHODS: The dataset comprised data from 2004 to 2010 from 2 sickness funds and one HIS. In both data sources, hospitalisations were restricted to admissions into one hospital with at least one diagnosis of heart failure. The 2 data sources were linked, in cases of the agreement of the admission and discharge dates, as well as the agreement of at least a certain percentage of diagnoses in HIS data when compared to SHI data (full coding depth). Based on the direct linkage using the pseudonymised insurance number as gold standard, the proposed linkage approach was evaluated by means of test statistics. Furthermore, the completeness of relevant information of the HIS was described. RESULTS: The dataset contained 3 731 hospitalisations from the HIS and 8 172 hospitalisations from the SHI routine data. The sensitivity of the linkage approach was 86.7% in the case of an agreement of at least 30% of the diagnoses and decreased to 41.7% in the case of 100% agreement in the diagnoses. The specificity was almost 100% at all studied cut-offs of agreement. Anthropometric measures and diagnostic information were available only for a small fraction of cases in the data of the HIS, whereas information on the health status and on laboratory information was comparatively complete. CONCLUSION: For the linkage of SHI routine data with complementary data sources, indirect linkage methods can be a valuable alternative in comparison to direct linkage, which is time-consuming with regard to planning and application. Since the proposed approach was used in a relatively small sample and a restricted patient population, a replication using nation-wide data without respective restrictions would require an extension of the algorithm. Furthermore, the large administrative effort seems questionable considering the comparatively high amount of missing values in interesting information in the HIS.

European Society for Pediatric Gastroenterology, Hepatology, and Nutrition guidelines for the diagnosis of coeliac disease.

OBJECTIVE: Diagnostic criteria for coeliac disease (CD) from the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) were published in 1990. Since then, the autoantigen in CD, tissue transglutaminase, has been identified; the perception of CD has changed from that of a rather uncommon enteropathy to a common multiorgan disease strongly dependent on the haplotypes human leukocyte antigen (HLA)-DQ2 and HLA-DQ8; and CD-specific antibody tests have improved. METHODS: A panel of 17 experts defined CD and developed new diagnostic criteria based on the Delphi process. Two groups of patients were defined with different diagnostic approaches to diagnose CD: children with symptoms suggestive of CD (group 1) and asymptomatic children at increased risk for CD (group 2). The 2004 National Institutes of Health/Agency for Healthcare Research and Quality report and a systematic literature search on antibody tests for CD in paediatric patients covering the years 2004 to 2009 was the basis for the evidence-based recommendations on CD-specific antibody testing. RESULTS: In group 1, the diagnosis of CD is based on symptoms, positive serology, and histology that is consistent with CD. If immunoglobulin A anti-tissue transglutaminase type 2 antibody titers are high (>10 times the upper limit of normal), then the option is to diagnose CD without duodenal biopsies by applying a strict protocol with further laboratory tests. In group 2, the diagnosis of CD is based on positive serology and histology. HLA-DQ2 and HLA-DQ8 testing is valuable because CD is unlikely if both haplotypes are negative. CONCLUSIONS: The aim of the new guidelines was to achieve a high diagnostic accuracy and to reduce the burden for patients and their families. The performance of these guidelines in clinical practice should be evaluated prospectively.

[Performance of record linkage for cancer registry data linked with mammography screening data]. / Zur Leistungsfähigkeit des Record-Linkage zwischen epidemiologischen Krebsregistern und dem Mammographie-Screening.

The evaluation of the German Mammography Screening Program requires record linkage with data from cancer registries in order to measure the number of false-negative mammograms and interval cancers. This study aims at evaluating the performance of the established linkage method based on identifiers encrypted by the standard procedure of the German cancer registries. In addition, the results are compared with an alternative method based on plain text identifiers. A total of 16,572 records from the Bremen Mammography Screening Pilot Study were linked with data from the Bremen Cancer Registry. Based on a gold standard set of matching record pairs, homonym and synonym errors were determined. Given the customary threshold value in cancer registries, the plain text method showed a lower rate of synonym errors (2.1-5.1%) and a lower rate of homonym errors (0.01-0.15%). As 10.4 million women are invited to take part biennially in screening, the corresponding figures would be 3,237 homonym errors for the standard procedure and 294 using the plain text method provided equivalent conditions. The 11-fold increase in the homonym error rate documents the trade-off for better data protection using encrypted data.

[Validation of secondary data. Strengths and limitations]. / Validierung von Sekundärdaten. Grenzen und Möglichkeiten.

Medical records databases (such as the General Practice Research Database-GPRD) and administrative databases (such as German Statutory Health Insurance (SHI) claims data) are useful sources for pharmacoepidemiology and health services research. However, these data are not primarily collected for research purposes. Validation studies are needed to examine their completeness and accuracy depending on the corresponding research question. This article reviews strategies for checks of internal consistency within the data from one SHI as well as between data from several SHIs and possibilities of internal data validation. Descriptive analyses of consistency can help to determine the integrity of data. The aim of internal validation is to separate uncertain from true cases based on information from secondary data alone or to reproduce known associations within the database. In addition external validation of secondary data is desirable using original prescriptions, medical records, hospital discharge letters and/or patient or physician interviews as a gold standard. A considerable number of external validation studies of diagnostic coding have been conducted within the GPRD. In contrast, such validation studies of German SHI claims data are mostly lacking and are urgently needed in the near future.

[Quality of diagnostic ICD coding for outpatients in Germany]. / Die ICD-Kodierqualität für Diagnosen in der ambulanten Versorgung.

The ICD-coding quality for outpatients' diagnoses by German physicians was analysed in a sample of five million members of the German Statutary Health Insurance System. New federal legislation coming into effect in 2009 for the reimbursement of physicians is based on patients' morbidity risks and thus on the quality of a provider's ICD coding. A sample of physicians' billing data for 2001-2003 containing ICD codes for patients' morbidity and the billed services was linked with outpatients' prescription data for the time period 2002- 2003. As in 2001-2003 information on the certainty of diagnosis was not yet mandatory, only 7.4% of all diagnoses were labelled as either "suspected diagnosis", "excluded diagnosis" or "history of diagnosis", hampering coding validity measurements. Chronic disease persisted in the time window analysed showing only minor successive prevalence decreases after an initial dip of at least 6% in the calendar term following the index term. The immediate decrease following the initial term may be due to initially suspected disease not confirmed until the work up at subsequent visits is completed. The slight downward slope after six months may indicate minor undercoding of chronic diagnoses. Few acute diagnoses persisted for longer than two calendar terms making it unlikely that acute diagnoses were erroneously maintained for repetitive reimbursement. Undercoding of diagnosis was abundant in patients receiving insulin prescriptions, as a diagnosis of diabetes was often missing. Numerous drugs prescribed could not be associated with a corresponding diagnosis coded by physicians. We suggest that before reimbursements to physicians are based on ICD-coded morbidity, a re-analysis of the data should be performed containing information on diagnosis certainty (mandatory since 2004) and the recently updated catalogue on fees for medical procedures provided "Einheitlicher Bewertungsmassstab" (EBM).

[Screening for colorectal cancer: what is the most effective strategy?]. / Früherkennung kolorektaler Tumoren: Gibt es die optimale Screeningmassnahme?

Colorectal cancer is one of the most common cancers in Western countries. The long natural history of colorectal cancer provides opportunities for detection of early stage cancer and for prevention of cancer by removal of adenomas. An effective screening technique should significantly reduce morbidity and mortality in the population. Several tests are available to screen healthy subjects at average risk for colorectal cancer: total colonoscopy, combined sigmoidoscopy and faecal occult blood test (FOBT), FOBT alone. At the present time clear evidence for the most effective screening strategy is not available. Colonoscopy screening in Germany needs an adequate tool to evaluate the programme. Follow up is essential and cancer registries would be an important partner.

[The Bremen mortality index]. / Der Bremer Mortalitätsindex.

The Bremen Mortality Index (BreMI) is an electronic data file providing all information found on death certificates of former Bremen citizens who have died after December 31, 1997. BreMI follows the example of the National Death Index (NDI) in the USA, which has provided information on the vital status of US citizens and cause of death since 1979. The Bremen Mortality Index has been linked successfully to the Bremen Cancer Registry and has improved the efficiency of following up cancer patients. A substantial number of death certificates may be checked automatically for the presence of a cancer diagnosis or any other diagnosis. The Bremen Mortality Index may be used as a primary source for data on particular causes of death. It will be used for developing a German thesaurus for automated coding of medical entities and for determining causes of death.

Gender differences in carpal tunnel syndrome? occupational and non-occupational risk factors in a population-based case-control study.

PURPOSE: To determine the role of occupational and personal risk factors of carpal tunnel syndrome (CTS) separately in men and women.METHODS: Men (n = 404) and women (n = 404) younger than 65 years with first surgery for CTS in 1995/96 were sampled at random from the Bremen population (0.65 million) and matched to controls by age and gender sampled from the population registry. A self-administered questionnaire with 77 questions inquired about personal factors and activities during work and private environment (response: 60% of eligible cases and 52% in controls, respectively).RESULTS: CTS risk increased with body mass index (BMI): odds ratio for each unit of BMI [kg/m(2)] OR(men) = 1.13; (95%-confidence-limits CL(men) 1.06, 1.20), OR(women) = 1.09 (CL(women) 1.04, 1.14). Multivariate analysis adjusting for BMI showed more pronounced risks in men compared with women for repetitive movements of the hand: OR(m) = 2.89 (CL 1.82, 4.58); OR(w) = 2.10 (CL 1.37, 3.22), for forceful grip: OR(m) = 2.69 (CL 1.70, 4.27); OR(w) = 2.29 (CL 1.43, 3.66), but not for household chores: OR(m) = 0.64 (CL 0.40, 1.03); OR(w) = 0.88 (CL 0.34, 2.29). Women worked less hours per week than men but manual exposures remained more relevant in men after adjustment. Exposure-response-relationships could be demonstrated for all work related exposures. Women were at higher risk for CTS if they had had more than two births or a history of hysterectomy. Adding these factors to the logistic model still showed an association between manual work and CTS. Blinded expert rating (manual vs. non-manual) of jobs held by respondents and non-respondents and by cases and controls did not reveal relevant selection effects or recall-bias.CONCLUSIONS: CTS is a work related disease in both men and women, the fraction attributable to work in the Bremen population under age 65 is estimated to be 33% in men and 15% in women. Funding: German Federal Ministry for Education & Research: 01 EG 9512.

Cardiovascular disease risk factors, CHD morbidity and mortality in the Federal Republic of Germany.

Analyses of data from the first National Health Examination Survey undertaken from 1984-1986 within the framework of the German Cardiovascular Prevention Study, show the following risk factor prevalences in 25-69 year-old men and women: overweight (BMI males: greater than 25, females greater than 24) or obese (BMI greater than 30): men 65.0%, women 57.6%; total serum cholesterol (less than 5.17 mmol/dl): men 73.7%, women 74.0%; normal blood pressure (according to JNC definitions): men 45.0%, women 59.1%; hypertension according to WHO criteria: men 26.0%, women 21.1%; controlled hypertensives (WHO criteria): men 19.9%, women 33.9%; current smoking: men 40.8%, women 26.1%. For most of the cardiovascular risk factors there is a clear negative association between prevalence and length of school education. Three myocardial infarction (MI) registries (WHO MONICA Project) are operating in the Federal Republic of Germany. Incidence and case-fatality data are within comparable ranges. Coronary heart disease (CHD) mortality has been relatively stable in both sexes from 1970 to 1986 with a minor peak in 1976 and a slight downward trend since then. A study of the reliability of coding procedures in West German state statistical offices revealed major disagreements so that trends derived from national mortality data as aggregate data of the federal states might be spurious. An ecological correlation of regional smoking prevalences (1978) and regional CHD mortality rates (1977-9) showed significant coefficients in men, but not in women.

[Coding of cause of death for mortality statistics--a comparison with results of coding by various statistical offices of West Germany and West Berlin]. / Verschlüsselung von Todesursachen für Mortalitätsstatistiken--Vergleich von Signierergebnissen in verschiedenen statistischen Amtern der Bundesrepublik Deutschland und West-Berlins.

1.136 death certificates representing all 1985 Bremen cardiovascular deaths and a 50%-sample of non-cardiovascular deaths in the age group 25-69 years were analyzed for reliability of nosologists' coding according to ICD-coding rules (9th revision). The 1.136 photocopied death certificates were used to assess intra-observer-variation in Bremen and to determine inter-observer-variation among 7 nosologists from 6 different State Statistical Offices and the Federal Statistical Office. Intra-observer-agreement in Bremen was found to be similar to the results presented in a comparable US-study: Bremen: 92.1%; Curb et al. 1983: 94.8%-96.1%; 3-digit-ICD-Code. Inter-observer-agreement was found to be much lower in Germany than in two US-studies: 3 coders agreeing on 3-digit-ICD-Code: Bremen: 67.7% (average, 3 coders out of 7); Curb et al.: 90.2% (3 coders); 3 coders agreeing on 4-digit-ICD-Code: Bremen: 61.5%; NCHS 1980: 90.3%. Agreement-rates were also much lower in Germany than in the USA (Curb et al.) when particular disease groups were analysed: Ischaemic heart disease (ICD 410-414): Bremen: 82.7% (average); USA: 97.2%; cerebrovascular disease (ICD 430-438): Bremen 65.6% (average); USA: 93.2%; neoplasms (ICD 140-239): Bremen: 94.0% (average); USA: 97.8%. We conclude that training, individual characteristics of nosologists, and other factors may cause important artifacts when comparing German mortality statistics on a regional level or during different time intervals.