The squeeze test is not accurate enough to be used on its own to diagnose arthritis in either the metacarpophalangeal (MCP) or metatarsophalangeal (MTP) joints, a cross-section cohort study has determined.
In a group of 152 patients, those who had a positive squeeze test -- where squeezing the hand or foot across the knuckle joints is unduly painful -- did have more swollen MCP joints than patients with a negative test at 0.97 (SD 1.42) versus 0.21 (SD 0.66; P<0.001).
Similarly, patients with a positive MTP squeeze test had more swollen MTP joints at 0.83 (SD 1.46) versus 0.24 (SD 0.74; P=0.004).
When the data on swollen joints were dichotomized, patients with a positive MCP squeeze test were over five times more likely to have arthritis in ≥1 MCP joints than patients with a negative test at an odds ratio (OR) of 5.2 (95% CI 2.2-12.2). Those with a positive MTP test were over three times as likely to have arthritis in ≥1 MTP joints as well (OR 3.3, 95% CI 1.4-7.8).
However, the sensitivity of the squeeze test at the MCP joint level was only 53% although the specificity was better at 82%.
For MTP joints, the sensitivity was again low at only 54% while the specificity was again higher at 74%.
Out of all MCP joints studied, the positive predictive value of the squeeze test was 42% (95% CI 34%-50%) while the negative predictive value was 88% (95% CI 83%-93%).
Out of all MTP joints studied, the positive predictive value was 30% (95% CI 23%-37%) while the negative predictive value was 89% (95% CI 84%-94%).
"GPs need tools to select patients with an increased chance of early arthritis [but] in this study, up to 50% of patients with swollen MCP or MTP joints at physical examination were missed by the squeeze test," W.B. van den Bosch, Leiden University Medical Center, Leiden, the Netherlands, and colleagues observe in the . "So the squeeze test should be combined with other tests to achieve a good discriminative ability."
Patients with arthralgia of recent-onset and either arthritis confirmed on physical examination or who were suspected of being at risk for arthritis based on expert rheumatology opinion were included in the study.
All patients underwent the "gold standard" physical joint examination by rheumatologists to confirm or rule out arthritis in either the MCP or MTP joints.
Patients also underwent MRI to detect subclinical joint inflammation, and MRI exams were scored using the RAMRIS score.
"In total, 25% of patients had a positive squeeze test at MCP joints, 31% had a positive squeeze test at MTP joints, and 14% had a positive squeeze test at both the MCP and MTP joints," the authors observe.
They also note that a positive MCP squeeze test was associated with a higher MRI inflammation score than a negative test (P<0.001) but this was not true for a positive MTP squeeze test that was not associated with a higher MRI inflammation score.
"Presently, no generally accepted test for early identification of arthritis (other than joint palpation) exists," researchers state.
"And clinicians should keep in mind the test characteristics of the squeeze test when performing this test in daily practice."
Disclosures
The study was funded by a Vidi grant of the Netherlands Organisation for Scientific Research.
The authors had no conflicts of interest to declare.
Primary Source
Annals of the Rheumatic Diseases
van den Bosch WB, et al "The diagnostic accuracy of the squeeze test to identify arthritis: a cross-sectional cohort study" Ann Rheum Dis 2015; DOI: 10.1136/annrheumdis-2014-207202.