[Practice variation in diagnostic testing for dementia; a nation-wide overview]. / Praktijkvariatie in aanvullend onderzoek bij dementie.

OBJECTIVE: To determine variation in diagnostic strategies for diagnosing dementia between Dutch hospitals. DESIGN: Descriptive, retrospective research based on claim data of Dutch health insurers. METHOD: Information on the use of diagnostic ancillary services carried out from 2015 to 2018 was collected via national-level insurance claims for patients who received a (new) diagnose-coding for dementia in 2018. Hospitals were included in the analysis if they diagnosed >50 patients with dementia. We distinguished academic medical centres (AMC), non-academic training hospitals (TH) and general hospitals (GH). RESULTS: In 2018, 20.073 new cases of dementia were diagnosed in 71 hospitals. The percentages of patients undergoing MRI/CT-imaging ranged from 37 to 99% (median 76.7%), neuropsychological-assessment from 0-89% (median 31.8%), cerebrospinal fluid examination from 0-14% (median 2.4%), PET/SPECT-imaging from 0-16% (median 6.2%) and electroencephalography from 1-20% (median 5.8%). Practice variation was comparable in AMCs, THs and GHs and was evidently skewed for PET/SPECT-imaging, electroencephalography and cerebrospinal fluid examination. There were no distinct differences according to case-mix characteristics or hospital volume. The percentage of patients subjected to ancillary diagnostic investigations decreased sharply with increasing age. CONCLUSION: In the Netherlands, diagnostic ancillary methods used vary widely between hospitals both in frequency and modality. This variation may be driven by limited evidence of diagnostic accuracy and added value of different diagnostic tests, variations in doctor and patient preferences and differences in available diagnostic techniques per hospital. Further exploration of this heterogeneity may help to identify a strategy that combines the most benefit with the least burden.