Photo by Juan D. Alfonso
Blood sample collection
Researchers say they have determined which blood tests can help general practitioners (GPs) rule out a diagnosis of multiple myeloma (MM).
The team discovered that plasma viscosity (PV) and erythrocyte sedimentation rate (ESR) were more helpful in ruling out MM than a C-reactive protein (CRP) test.
Furthermore, the possibility of MM “is extremely low” in patients with normal hemoglobin (Hb) and normal PV or ESR.
“Ordinarily, a GP will see a patient with myeloma every 5 years, and early diagnosis matters,” said study author William Hamilton, MD, of the University of Exeter Medical School in the UK.
“We report a simple way a GP can check patients presenting symptoms such as back, rib, and chest pain or recurrent chest infections and determine whether they have myeloma or not.”
Dr Hamilton and his colleagues reported their findings in the British Journal of General Practice.
The researchers analyzed blood tests performed on 2703 MM patients up to 5 years prior to diagnosis. The team then compared results in the MM cases to blood test results in 12,157 patients without MM, matched for age and other relevant parameters.
The researchers used likelihood ratios (LRs) to classify tests as useful for ruling in or ruling out MM.
The team explained that positive likelihood (LR+) tests indicate how many times more likely a positive test occurs in individuals with MM than in those without the disease. Negative likelihood (LR–) tests indicate how many times less likely a negative result will occur in individuals with MM than in those without MM.
A test was defined as useful for ruling in MM if the LR+ was ≥ 5 and useful for ruling out MM if the LR– was ≤ 0.2.
Results
None of the inflammatory markers analyzed proved useful (LR+ ≥ 5) for ruling in MM.
The LR+ was:
- 2.0 for raised PV
- 1.9 for raised ESR
- 1.2 for raised CRP.
Similarly, none of the tests alone was useful (LR– ≤ 0.2) for ruling out MM.
The LR– was:
- 0.42 for normal Hb
- 0.81 for normal calcium
- 0.80 for normal creatinine
- 0.28 for normal ESR
- 0.32 for normal PV
- 0.87 for normal CRP.
However, several combinations of tests were useful for ruling out MM.
| Tests | LR– (95% CI) |
| Hb and PV | 0.12 (0.07 to 0.23) |
| Hb and ESR | 0.16 (0.13 to 0.21 |
| Hb, creatinine, and PV | 0.09 (0.04 to 0.20) |
| Hb, calcium, and PV | 0.06 (0.02 to 0.18 |
| Hb, creatinine, and ESR | 0.16 (0.12 to 0.21) |
| Hb, calcium, and ESR | 0.16 (0.12 to 0.22) |
| Hb, calcium, creatinine, and PV | 0.06 (0.02 to 0.19) |
| Hb, calcium, creatinine, and ESR | 0.17 (0.12 to 0.24) |
| Hb and CRP* | 0.39 (0.32 to 0.47)* |
| Hb, creatinine, and CRP* | 0.33 (0.26 to 0.42)* |
| Hb, calcium, and CRP* | 0.33 (0.25 to 0.42)* |
| Hb, calcium, creatinine, and CRP* | 0.31 (0.22 to 0.42)* |
| *Not useful (LR– ≤0.2) | |
Conclusions/implications
The researchers concluded that, with normal Hb and normal PV or ESR, the possibility of MM is very low, and assessing CRP or creatinine as well increases the sensitivity of testing only slightly.
“The combination of levels of hemoglobin . . . and 1 of 2 inflammatory markers [ESR or PV] are a sufficient test rule out myeloma,” said study author Constantinos Koshiaris, of the University of Oxford in the UK.
“If abnormalities are detected in this test, it should lead to urgent urine protein tests, which can help speed up diagnosis.”
The researchers also recommend adding calcium tests if patients have certain symptoms, such as back pain, rib pain, joint pain, and fracture.