Quantitative sacroiliac scintiscanning: a sensitive and objective method for assessing efficacy of nonsteroidal, anti-inflammatory drugs in patients with sacroiliitis.

Serial computer assisted quantitative sacroiliac scintiscanning (SI joint/sacrum ratios) 3 hours after low dosage (5 mCi) 99mTc methylene diphosphonate has been used as an objective index of sacroiliitis in a single blind 14-day cross-over comparison of azapropazone 600 mg b.d. and naproxen 500 mg b.d. in 18 patients with active sacroiliitis. Clinical assessments included visual analogue scales for measurement of pain and early morning stiffness, chest expansion, a modified Schober test, and goniometric measurement of thoracolumbar spinal flexion by means of an inclinometer. Statistically significant decreases in pain (p less than 0.001) and early morning stiffness (p less than 0.001) followed treatment with each NSAID, but there was no significant difference in the fall in these parameters, although 15 out of 18 patients expressed a preference for naproxen. Chest expansion and thoracolumbar flexion were not significantly affected by either drug. Serial quantitative scintigraphy showed a mean fall in joint sacrum ratios following each treatment which was statistically significant (p less than 0.02) only after naproxen. Serial quantitative scintigraphy can be used as an objective method of assessing sacroiliitis and was sufficiently sensitive to reflect the patients' subjective preference in a short-term comparison of 2 NSAID.