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.

IgA-EmA and IgA-anti-TG2 tests appear highly accurate to diagnose CD. IgG-anti-DGP tests may help in excluding CD. IgA-AGA and IgA-DGP tests show inferior accuracy. POC tests may achieve high accuracy in the hands of experienced readers, but IgA-anti-TG2/EmA were superior.

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The causation of CTS by occupational activities, either alone or in combination with other factors, has been well documented by epidemiological data and is pathophysiologically plausible. In Germany, a physician who diagnoses carpal tunnel syndrome in an employee with a relevant, damaging occupational exposure is required to report the case to the German Social Accident Insurance.

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.

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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).

No abstract