Preventing overuse of laboratory diagnostics: a case study into diagnosing anaemia in Dutch general practice

BACKGROUND: More information is often thought to improve medical decision-making, which may lead to test overuse. This study assesses which out of 15 laboratory tests contribute to diagnosing the underlying cause of anaemia by general practitioners (GPs) and determines a potentially more efficient subset of tests for setting the correct diagnosis. METHODS: Logistic regression was performed to determine the impact of individual tests on the (correct) diagnosis. The statistically optimal test subset for diagnosing a (correct) underlying cause of anaemia by GPs was determined using data from a previous survey including cases of real-world anaemia patients. RESULTS: Only 9 (60%) of the laboratory tests, and patient age, contributed significantly to the GPs' ability to diagnose an underlying cause of anaemia (CRP, ESR, ferritin, folic acid, haemoglobin, leukocytes, eGFR/MDRD, reticulocytes and serum iron). Diagnosing the correct underlying cause may require just five (33%) tests (CRP, ferritin, folic acid, MCV and transferrin), and patient age. CONCLUSIONS: In diagnosing the underlying cause of anaemia a subset of five tests has most added value. The real-world impact of using only this subset should be further investigated. As illustrated in this case study, a statistical approach to assessing the added value of tests may reduce test overuse

Long-term outcomes in patients newly diagnosed with iron deficiency anaemia in general practice: A retrospective cohort study

Objectives To describe all iron deficiency anaemia (IDA)-related causes during follow-up of patients newly diagnosed with IDA and to assess whether a delayed colorectal cancer (CRC) diagnosis influences survival. Design and setting Retrospective cohort study of patients from general practices in the Dordrecht area, the Netherlands. Participants Men and women aged ≥50 years with a new diagnosis of IDA (ie, no anaemia 2 years previously). Method From February 2007 to February 2018, all relevant data were collected from the files of the referral hospital. Early IDA-related cause was defined as established within 18 weeks after IDA diagnosis. Cox proportional-hazards regression was u

Diagnostic Work-Up of Anemia in General Practice

The underlying cause of anemia can be found starting with the establishment of the anemia etiology. In this thesis, we investigated the cost-effectiveness of an extensive laboratory panel to find the anemia etiology in general practice

The accuracy of mean corpuscular volume guided anaemia classification in primary care

BACKGROUND: Anemia can be categorized into micro-, normo- or macrocytic anemia based on the mean corpuscular volume (MCV). This categorization might help to define the etiology of anemia. METHODS: The cohort consisted of patients newly diagnosed with anaemia in primary care. Seven aetiologies of anaemia were defined, based on an extensive laboratory protocol. Two assumptions were tested: (i) MCV 100 fl (macrocytic) excludes iron deficiency anaemia, anaemia of chronic disease and renal anaemia as anaemia aetiology. RESULTS: Data of 4129 patients were analysed. One anaemia aetiology could be assigned to 2422 (59%) patients, more than one anaemia aetiology to 888 (22%) patients and uncertainty regarding the aetiology remained in 819 (20%) patients. MCV values were within the normal range in 3505 patients (85%). In 59 of 365 microcytic patients (16%), the anaemia aetiology was not in accordance with the first assumption. In 233 of 259 macrocytic patients (90%), the anaemia aetiology was not in accordance with the second assumption. CONCLUSIONS: Anaemia aetiologies might be ruled out incorrectly if MCV guided classification is used as a first step in the diagnostic work-up of anaemia. We recommend using a broader set of laboratory tests, independent of MCV

Kinetic analysis and simulation studies for lipase-catalysed resolution of racemic 2-methyl-1-pentanol

The lipase-catalysed optical resolution of a racemic mixture of 2-methyl-1-pentanol by transesterification using vinyl acetate as acyl donor has been studied experimentally. A mechanistic model has been developed for the double-substrate reaction sequence treating both enantiomers as competing substrates. The model is based upon a ping-pong mechanism with alternative substrates involving an acyl-enzyme intermediate. The kinetic constants of the model have been evaluated using initial rate experiments and nonlinear regression analysis. The model successfully predicts the evolution of the enantiomeric excess of substrate (eeR) and the degree of conversion with time for batch experiments with various initial concentrations of vinyl acetate and (R,S)-2-methyl-1-pentanol. Furthermore, the rate equations have been used to theoretically study the dynamic progression of a continuous enzyme-catalysed resolution process. The enantiomeric excess as a function of conversion for different process configurations is discussed. It is found, that the maximum attainable eeR is strongly dependent on the residence time distribution of the continuous reactor and is rather low for a continuous stirred tank reactor (CSTR) due to competitive inhibition effects

The effectiveness of a routine versus an extensive laboratory analysis in the diagnosis of anaemia in general practice

Background: We investigated the percentage of patients diagnosed with the correct underlying cause of anaemia by general practitioners when using an extensive versus a routine laboratory work-up. Methods: An online survey was distributed among 836 general practitioners. The survey consisted of six cases, selected from an existing cohort of anaemia patients (n = 3325). In three cases, general practitioners were asked to select the laboratory tests for further diagnostic examination from a list of 14 parameters (i.e. routine work-up). In the other three cases, general practitioners were presented with all 14 laboratory test results available (i.e. extensive work-up). General practitioners were asked to determine the underlying cause of anaemia in all six cases based on the test results, and these answers were compared with the answers of an expert panel. Results: A total of 139 general practitioners (partly) responded to the survey (17%). The general practitioners were able to determine the underlying cause of anaemia in 53% of cases based on the routine work-up, whereas 62% of cases could be diagnosed using an extensive work-up (P = 0.007). In addition, the probability of a correct diagnosis decreased with the patient’s age and was also affected by the underlying cause itself, with anaemia of chronic disease being hardest to diagnose (P = 0.003). Conclusion: The use of an extensive laboratory work-up in patients with newly diagnosed anaemia is expected to increase the percentage of correct underlying causes established by general practitioners. Since the underlying cause can still not be established in 31.3% of anaemia patients, further research is necessary