Investigation momentum: the relentless pursuit to resolve uncertainty

Risk variables associated with abnormal calcium, magnesium and phosphate levels among emergency department patients

OBJECTIVE

The utility of calcium, magnesium and phosphate measurement in the ED is limited. We aimed to determine clinical risk variables for abnormal levels of these electrolytes in order to inform the development of an ordering guideline.

METHODS

We performed a retrospective, observational study of patients who presented to a tertiary referral ED between January and June 2017. Adult patients who had serum calcium, magnesium or phosphate tests completed during their ED stay were included. Presenting symptoms and signs, comorbidities, medication use and laboratory values were extracted from the medical record. Patients with missing data items were excluded. Logistic regression models determined clinical risk variables associated with low and high levels of each electrolyte.

RESULTS

A total of 33 120 adults presented during the study period. Of the 1679 calcium, 1576 magnesium and 1511 phosphate tests, 228 (13.6%), 158 (10.0%) and 387 (25.6%) were abnormal, respectively. Significant risk variables (P < 0.05) for abnormal levels were: hypocalcaemia - vomiting, perioral numbness, hand/foot spasm, calcium and phosphate supplements and chemotherapy (odds ratio [OR] range 5.9-17.3); hypercalcaemia - female sex, vomiting, polyuria, confusion, hyperparathyroidism, cancer and type 1 diabetes (OR range 2.3-9.7); hypomagnesemia - female sex, proton pump inhibitor use, tacrolimus use, alcohol abuse and type 2 diabetes (OR range 2.2-13.1); hypermagnesemia - lethargy, thiazide use and chronic kidney disease (OR range 4.3-4.5); hypophosphatemia - nausea, seizure and glucocorticoid use (OR range 1.7-2.1); and hyperphosphataemia - polyuria, diuretics and chronic kidney disease (OR range 1.9-5.0).

CONCLUSION

A range of demographic, comorbid, medication and clinical variables are associated with abnormal calcium, magnesium and phosphate levels. These findings will inform the development of clinical guidelines to rationalise calcium, magnesium and phosphate testing. Justification may be required for testing patients with no risk variables.

Utility of calcium, magnesium and phosphate testing in the emergency department

OBJECTIVE

To determine how frequently calcium (Ca), magnesium (Mg) and phosphate (PO₄ ) tests change ED patient management.

METHODS

We undertook a retrospective observational study in an Australian tertiary referral ED. We enrolled adult patients (aged ≥18 years) who presented between 1 January and 30 June 2017 and who had a serum Ca, Mg or PO₄ test ordered and completed during their ED stay. Patient symptoms, medical history, electrolyte levels and ED management changes were extracted from the electronic medical record.

RESULTS

Of the 33 120 adults presented during the study period, 1716 (5.2%, 95% confidence interval [CI] 5.0-5.4) had at least one Ca, Mg or PO₄ test completed in the ED. This included 4776 individual electrolyte tests, of which 776 (16.2%, 95% CI 15.2-17.3) were abnormal. Fifty-six (7.2% [95% CI 5.5-9.3] of patients with abnormal tests, 1.2% [95% CI 0.9-1.5] of all tests) tests were associated with a change in ED management. Twenty-six out of 1683 (1.5%) Ca levels were low with six (23.1%) management changes; 203 (12.1%) were high with 10 (4.9%) management changes. One hundred and twenty-eight out of 1579 (8.1%) Mg levels were low with 33 (25.8%) management changes; 30 (1.9%) were high with no management changes. Two hundred and twenty-five out of 1514 (14.9%) PO₄ levels were low with six (2.7%) management changes; 164 (10.8%) were high with one (0.6%) management change. Fifty (2.9%) patients had management changes despite normal electrolyte levels.

CONCLUSION

Ca, Mg and PO₄ testing is common. However, the yield of clinically significant abnormal levels is low and patient management is rarely changed. Testing of these electrolytes needs to be rationalised.

What do tests do for doctors? A qualitative study of blood testing in UK primary care

BACKGROUND

Rates of blood testing are rising with significant geographical variability. Most research into diagnostic testing focuses on the role of tests in diagnostic decision-making.

OBJECTIVE

The aim of this study was to explore the non-medical motives for blood testing by considering what tests do for doctors, through qualitative interviews with general practitioners (GPs).

METHODS

We undertook 23 in-depth semi-structured interviews with UK GPs. Reasons for performing recent inflammatory marker blood tests were explored by reviewing GPs pathology inboxes to ground discussions in real-life clinical practice. Interviews were transcribed verbatim and analysed using a grounded theory approach.

RESULTS

Blood tests offer doctors a tool to manage uncertainty; within a context of increased litigation, risk aversion and reduced continuity of care. Tests can also be offered as a 'gift' for patients, a way to be seen to be 'doing something'; in the social context of time pressures and perceived patient pressures. There was a tension however. On the one hand, doctors talked about using tests for reassurance and as a 'gift' offering 'truth'. Yet paradoxically, they also discussed the challenges of uncertainty and anxiety from inconclusive test results.

CONCLUSION

Our study emphasises that defining 'unnecessary' blood testing may not be as simple as determining medical criteria for testing; psychosocial reasons may be equally valid and interlinked. Further research is needed to help GPs manage uncertainty within the context of a risk averse society, and to explore the congruence and dissonance between doctors' and patients' perceptions of testing.

A Practical Framework for Understanding and Reducing Medical Overuse: Conceptualizing Overuse Through the Patient-Clinician Interaction

Overuse of medical services is an increasingly recognized driver of poor-quality care and high cost. A practical framework is needed to guide clinical decisions and facilitate concrete actions that can reduce overuse and improve care. We used an iterative, expert-informed, evidence-based process to develop a framework for conceptualizing interventions to reduce medical overuse. Given the complexity of defining and identifying overused care in nuanced clinical situations and the need to define care appropriateness in the context of an individual patient, this framework conceptualizes the patient-clinician interaction as the nexus of decisions regarding inappropriate care. This interaction is influenced by other utilization drivers, including healthcare system factors, the practice environment, the culture of professional medicine, the culture of healthcare consumption, and individual patient and clinician factors. The variable strength of the evidence supporting these domains highlights important areas for further investigation. Journal of Hospital Medicine 2017;12:346-351.

Quality Improvement Intervention for Reduction of Redundant Testing

Laboratory data are critical to analyzing and improving clinical quality. In the setting of residual use of creatine kinase M and B isoenzyme testing for myocardial infarction, we assessed disease outcomes of discordant creatine kinase M and B isoenzyme +/troponin I (-) test pairs in order to address anticipated clinician concerns about potential loss of case-finding sensitivity following proposed discontinuation of routine creatine kinase and creatine kinase M and B isoenzyme testing. Time-sequenced interventions were introduced. The main outcome was the percentage of cardiac marker studies performed within guidelines. Nonguideline orders dominated at baseline. Creatine kinase M and B isoenzyme testing in 7496 order sets failed to detect additional myocardial infarctions but was associated with 42 potentially preventable admissions/quarter. Interruptive computerized soft stops improved guideline compliance from 32.3% to 58% (P < .001) in services not receiving peer leader intervention and to >80% (P < .001) with peer leadership that featured dashboard feedback about test order performance. This successful experience was recapitulated in interrupted time series within 2 additional services within facility 1 and then in 2 external hospitals (including a critical access facility). Improvements have been sustained postintervention. Laboratory cost savings at the academic facility were estimated to be ≥US$635 000 per year. National collaborative data indicated that facility 1 improved its order patterns from fourth to first quartile compared to peer norms and imply that nonguideline orders persist elsewhere. This example illustrates how pathologists can provide leadership in assisting clinicians in changing laboratory ordering practices. We found that clinicians respond to local laboratory data about their own test performance and that evidence suggesting harm is more compelling to clinicians than evidence of cost savings. Our experience indicates that interventions done at an academic facility can be readily instituted by private practitioners at external facilities. The intervention data also supplement existing literature that electronic order interruptions are more successful when combined with modalities that rely on peer education combined with dashboard feedback about laboratory order performance. The findings may have implications for the role of the pathology laboratory in the ongoing pivot from quantity-based to value-based health care.

'I'm fishing really'--inflammatory marker testing in primary care: a qualitative study

Background

Inflammatory markers can be helpful as part of the diagnostic workup for specific diseases or for monitoring disease activity. A third use is as a screening and/or triage tool to differentiate between the presence or absence of disease. Most research into inflammatory markers looks at diagnosis of specific diseases and comes from secondary care. Qualitative studies to explore when and why clinicians use these tests in primary care are lacking.

Aim

To identify clinicians’ approaches to inflammatory marker testing in primary care.

Design and setting

Qualitative study with 26 GPs and nurse practitioners.

Method

Interviews were conducted using a semi-structured topic guide. Clinicians reviewed recent cases of inflammatory marker testing in their pathology inbox. Interviews were audiorecorded and transcribed. Qualitative analysis was conducted by two of the authors.

Results

Clinicians are uncertain about the appropriate use of inflammatory markers and differ in their approach to testing patients with undifferentiated symptoms. Normal or significantly elevated inflammatory markers are seen as helpful, but mildly raised inflammatory markers in the context of non-specific symptoms are difficult to interpret. Clinicians describe a tension between not wanting to ‘miss anything’ and, on the other hand, being wary of picking up borderline abnormalities that can lead to cascades of further tests. Diagnostic uncertainty is a common reason for inflammatory marker testing, with the aim to reassure; however, paradoxically, inconclusive results can generate a cycle of uncertainty and anxiety.

Conclusion

Further research is needed to define when inflammatory marker testing is useful in primary care and how to interpret results.