Urine dipstick testing may be adequate to rule out urinary tract infection (UTI) in febrile infants while waiting for urine culture results, according to a retrospective observational study of 6,394 infants ages 1 to 90 days.
Urine dipstick is less expensive to perform than microscopy of centrifuged urine and can be done in office settings without special training. Studies have shown that dipstick is a good stand-alone screening test for UTI in children ages 2 and older, but data on its effectiveness in younger children are lacking.
This study compared dipstick results in febrile children ages 1-90 days with microscopy and combined urinalysis (dipstick plus microscopy).
Researchers identified febrile infants who received care at one of 23 hospitals in Utah between 2004 and 2011. All infants had catheterized urine dipstick, microscopic urinalysis and urine bacterial cultures performed at the same time.
Results showed 12% of patients had cultures positive for UTI. The sensitivity of combined urinalysis was greater than for dipstick alone (94.7% vs. 90.8%). The specificity of dipstick was greater than combined urinalysis (93.8% vs. 87.6%) or microscopy (93.8% vs. 91.3%).
In addition, the positive predictive value of dipstick (66.8%) was greater than combined urinalysis (51.2%) or microscopy (58.6%). Finally, the negative predictive value of combined urinalysis was greater than dipstick only in infants older than 28 days (99.2% vs. 98.7%).
The authors noted that performing urine microscopy in infants 29-90 days would be expected to result in up to eight infants with false-positive screens for UTI for every one infant missed by dipstick. They concluded that urine dipstick test may be an adequate stand-alone screen for UTI in febrile infants ages 29-90 days while awaiting urine culture results.
Comment: I always order a dipstick assessment (for leucocyte esterase & nitrites) for infants with fever, since this is a rapid non invasive test that help diagnose a UTI that is otherwise many a times missed by doctors in private practice in India.