Although histological proof of GCA is the gold standard, temporal artery biopsy is seldom done these days because:
1) the biopsied segment may not contain the pathology (skip lesions, sampling error), as this study demonstrates;
2) we have non-invasive diagnostic tools like ultrasound, CT angiogram and PET scan with good sensitivity and specificity, some of which being able to delineate extent of vessels involved;
3) patients don't like surgical procedures if they can help it, especially if complications can happen, though uncommon (skin necrosis, scarring, haematoma, etc).
This study suggests 4 predictors of the diagnosis:
1) persistent headaches;
2) jaw claudication (ache with chewing);
3) elevated platelet count;
4) elevated ESR.
These will not eliminate the need for imaging, but rather steer the diagnostic workup towards imaging.