828 The Journal of Rheumatology 2005; 32:5 Can the Urine Dipstick Test Reduce the Need for Microscopy for Assessment of Systemic Lupus Erythematosus Disease Activity? REBECCAWING-YAN CHAN, KAI-MING CHOW, LAI-SHAN TAM, EDMUND KWOK-MING LI, SIU MAN WONG, PHILIP KAM-TAO LI, and CHEUK-CHUN SZETO ABSTRACT. Objective. Urine microscopic examination is an important component of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). We investigated whether the urine dipstick test can reduce the need for microscopy for the assessment of SLEDAI. Methods. We studied 269 urine samples from 259 SLE patients with Albustix™ and Hemastix™ reagent strips. The results were compared to concomitant microscopic examination of urinary sedi- ment. Results. When trace red blood cell was defined as the cutoff, the sensitivity, specificity, and nega- tive predictive value (NPV) of the Hemastix urine test were 0.98, 0.53, and 0.99, respectively, for hematuria; 0.82, 0.47, and 0.90, respectively, for the presence of pyuria; and 0.91, 0.44, and 0.98, respectively, for the presence of casts by microscopic examination. When proteinuria of 1+ was defined as the cutoff, the sensitivity, specificity, and NPV of the Albustix test were 1.00, 0.46, and 0.99, respectively, for urinary casts; and 0.82, 0.49, and 0.90, respectively, for the presence of pyuria. When both Albustix and Hemastix were applied as screening test, urine microscopy could be reduced by 27%; however, 8% of cases with normal Albustix and Hemastix tests had at least one abnormality on urine microscopy examination. Conclusion. In patients with SLE, a combination of Albustix and Hemastix urine tests showed rea- sonable sensitivity to detect abnormalities in urine sediment. Based on these results, routine urine microscopy can be limited to SLE patients with abnormal Albustix or Hemastix tests. Rarer causes of abnormal renal function in lupus, such as tubulointerstitial nephritis or drug induced interstitial nephritis, would be manifested by pyuria and therefore would not necessarily be detected by changes in the blood and protein detectors on the urine dipstick. (J Rheumatol 2005;32:828–31) Key Indexing Terms: SYSTEMIC LUPUS ERYTHEMATOSUS DIPSTICK HEMATURIA PROTEINURIA SYSTEMIC LUPUS ERYTHEMATOSUS DISEASE ACTIVITY INDEX From the Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China. Supported in part by Chinese University of Hong Kong research accounts 6900972 and 6900570. R.W-Y. Chan, BSc(Hons), Research Assistant; K-M. Chow, MBChB, MRCP(UK), Fellow; L-S. Tam, MBChB, MRCP(UK), Fellow; E.K-M. Li, MD, FRCPC, Associate Professor; S-M. Wong, MBBS, MRCP(UK), Fellow; P.K-T. Li, MD, FRCP, Consultant; C-C. Szeto, MD, FRCP(Edin), Associate Professor. Address reprint requests to Dr. C.C. Szeto, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong. E-mail: ccszeto@cuhk.edu.hk Accepted for publication December 20, 2004. Systemic lupus erythematosus (SLE) is a systemic autoim- mune disease with high morbidity and mortality 1,2 . The aber- rant immune response of SLE triggers attacks to multiple organ systems, resulting in a variety of clinical manifesta- tions 3 . SLE usually runs a course with disease flares and remissions. As a result, regular assessment of disease activ- ity is necessary. The Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) is one of the most com- monly used clinical tools for assessment and monitoring of SLE disease activity 4 . Among other clinical and laboratory measures of the SLEDAI score, it requires microscopic examination of the urinary sediment. Reagent strip testing of urine specimens is commonly used as a screening tool in many areas of clinical practice 5-8 . With the use of reagent strips, a preliminary assessment of possible findings in the urinary sediment can be obtained rapidly and conveniently; cost and time may be saved by reducing the need for formal microscopic examination of many normal urine specimens. The value of the urine strip test as a screening tool has been demonstrated in other clin- ical settings 8-10 ; we investigated whether urine strip testing can be used as a screening tool for assessment of SLE dis- ease activity. MATERIALS AND METHODS Patient selection. Two hundred sixty-nine consecutive urine samples were collected from 259 SLE patients. All patients fulfilled the American College of Rheumatology diagnostic criteria for SLE 11 . Disease activity of SLE at the time of urine collection was assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) 12 by independent clini- Personal non-commercial use only. The Journal of Rheumatology Copyright © 2005. All rights reserved. www.jrheum.org Downloaded on September 7, 2022 from