The tourniquet ischemia test (IT) has a high positive predictive value (PPV) of 85% for diagnosis of complex regional pain syndrome (CRPS) and could be a useful confirmatory test, but low sensitivity (49%) means it is not appropriate for screening.
Why this matters
CRPS is usually diagnosed based on clinical symptoms and history due to the absence of any definitive biomarker or test.
The IT was developed following a researcher’s observation that distal pain increased with elevation and decreased with lowering of the affected area in patients diagnosed with reflex sympathetic dystrophy and suffering continuous distal pain.
The IT is a simple, time-efficient and inexpensive test, but is not currently in common use for diagnosing suspected CRPS. Hence, there is limited evidence as to the diagnostic performance or potential of this test.