Background The squeeze test (a.k.a Gaenslen's Compression Maneuver) consists on the compression of the metacarpal-phalangeal (MCP) joints to elicit pain in a patient with active synovitis. The squeeze test has three main purposes: Screening of inflammatory arthritis, as a predictor of rheumatoid arthritis in arthralgia patients, and as a quick and practical evaluation of the presence/absence of synovitis in patients already diagnosed with RA. The force and the way to perform the squeeze test had been evaluated in rheumatologists on a biomechanical device, with conflicting results. We developed a biomechanical device to perform the squeeze test.
Objectives Our aim is to determine the force whether the automated squeeze test discriminate patients with active RA from inactive ones. And the force that differentiates a healthy patient from a RA patient.
Methods Observational study in RA (ACR/EULAR 2010) patients and healthy persons. We perform 3-squeeze test on the device in the MCP joints and record the force enough to elicit pain. And then compare them with the joint counts by the clinician
Results Two hundred MCP joints from 50 hands were tested. From 25 RA patients with a mean age of 54.6 years (SD 11.22), with a mean disease latency of 1.2 years (SD 2.7). The total swollen joint count was 16 (7 right joints + 9 left joints) and 70 total tender joint count (30 right joints and 40 left joints). The median of force that caused pain in the RA patient's right hand was 3.07 kg (IQR 2.4) and the left hand was 2.78 kg (IQR 3.8). The cut-off for the force to detect a tender right hand joint was 1,020 grams with a sensitivity of 100% and specificity of 10%; for a swollen right hand joint was 1,400 with a sensitivity of 100% and specificity of 28.6%. For a tender left hand joint was 1620 grams with a sensitivity 70% and specificity of 6.7%; and for a swollen left joint was 1990 grams with a sensitivity of 100% and specificity of 27.3%.
In the second phase, 560 MCP joints of 140 hands from 70 healthy volunteers were compressed. The median force to elicit pain in the right hand was 4.2 kg (IQR 9.5) vs. 3.07 kg (IQR 8.7) from RA patients (p=0.003). And for left hand 4.6 kg (IQR 9.7) vs. 2.78 kg (IQR 9.2) from RA (p=0.014).
Conclusions It is necessary to continue the exploration of the maneuver in different clinical settings. Validate the strength in patients with different arthropathies, activity levels and different clinical stages (screening, activity, prediction) and also with imaging methods for evidence of inflammation (US, MRI)
Disclosure of Interest None declared