Dipstick testing of urine--can it replace urine microscopy?

One thousand consecutive urine specimens were studied to assess the sensitivity of a commercially available dipstick (Chemstrip 8, Boehringer Mannheim Corp., Indianapolis, IN) to predict the presence or absence of microscopic abnormalities. The Chemstrip 8 had a sensitivity of 78%, specificity of 54%, and a false negative rate of 38%. An additional 1,000 consecutive urine specimens were then studied using the Chemstrip 9, a reagent dipstick that includes the leukocyte esterase (LE) test. The Chemstrip 9 had a sensitivity of 82%, specificity of 42%, and a false negative rate of 36%. Chi-squared analysis revealed that the two dipsticks were not significantly different (chi 2 = 0.17, P greater than 0.5). Clinical review of patients with false negative results showed that approximately one-third to one-half of these patients had either spinal cord injury or genitourinary problems. Maximal potential savings in workload of approximately 10% were found if microscopic examinations were to be performed only on urine specimens with abnormal dipsticks. Our data suggest that in our patient population, we should not eliminate microscopic urine examination based on abnormal dipstick findings.