Physicians and patients alike dislike unnecessary tests that screen for diseases the patients aren’t likely to have. Of course, it can’t be known ahead of time that those tests are unnecessary. Or can it? In one study at least, investigators were able to narrow the focus so finely that their model reduced the number of patients who underwent screening by 30%, while correctly predicting disease—in this case retinopathy of prematurity—100% of the time. The research was published in the July issue of JAMA Ophthalmology.

The study took a retrospective look at 7,483 premature infants to develop its six-point retinopathy of prematurity predictive model. Infants who met any of these criteria would undergo examinations:

1. A gestational age of younger than 28 weeks.
2. A birth weight of less than 1,051g.
3. A weight gain of less than 120g 10 to 19 days after birth.
4. A weight gain of less than 180g 20 to 29 days after birth.
5. A weight gain less than 170g during 30 to 39 days after birth.
6. A diagnosis of hydrocephalus.

During the study, these criteria predicted 459 of 459 (100%) type 1 cases, 524 of 524 (100%) treated cases and 466 of 472 (98.7%) type 2 cases. With validation, the investigators say, the criteria could be incorporated into screening guidelines to reduce the number of infants who require exams.