Early detection of multiple myeloma in primary care using blood tests: a case–control study in primary care

Journal article

Background: Multiple myeloma is a haematological cancer characterised by numerous non-specific symptoms leading to diagnostic delay in a large proportion of patients.

Aim: To identify which blood tests are useful in suggesting or excluding a diagnosis of myeloma.

Design and setting: A matched case–control study set in UK primary care using routinely collected data from the Clinical Practice Research Datalink.

Method: Symptom prevalence and blood tests were analysed up to 5 years before diagnosis in 2703 cases and 12 157 matched controls. Likelihood ratios (LR) were used to classify tests or their combinations as useful rule-in tests (LR+ = ≥5), or rule-out tests (LR− = ≤0.2).

Results: Raised plasma viscosity (PV) had an LR+ = 2.0, 95% confidence interval [CI] = 1.7 to 2.3; erythrocyte sedimentation rate (ESR) 1.9, 95% CI = 1.7 to 2.0; and C-reactive protein (CRP) 1.2, 95% CI = 1.1 to 1.4. A normal haemoglobin had an LR− = 0.42, 95% CI = 0.39 to 0.45; calcium LR− = 0.81, 95% CI = 0.78 to 0.83; and creatinine LR− = 0.80, 95% CI = 0.77 to 0.83. The test combination with the lowest LR− was all normal haemoglobin with calcium and PV, which had an LR− = 0.06, 95% CI = 0.02 to 0.18, though the LR− for normal haemoglobin and PV together was 0.12 (95% CI = 0.07 to 0.23).

Conclusion: Plasma viscosity and ESR are better for both ruling in and ruling out the disease compared with C-reactive protein. A combination of a normal ESR or PV and normal haemoglobin is a simple rule-out approach for patients currently being tested in primary care.

Authors: Koshiaris, C; Van Den Bruel, A; Oke, J; Nicholson, B; Shephard, E

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Royal College of General Practitioners
• Journal: British Journal of General Practice
• Volume: 68
• Issue: 674
• Pages: e586-e593
• Publication date: 2018-08-13
• Acceptance date: 2018-03-14
• DOI: 10.3399/bjgp18X698357
• ISSN: 0960-1643, 1478-5242
• Keywords: multiple myeloma; blood; case–control studies; primary care; diagnosis; inflammatory