Alaska Blind Child Discovery
Medicaid P4P
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P4P is a proposal to "pay for performance." Many pediatric ophthalmologists would like this to happen for pediatric vision screening. However, not all pediatric ophthalmologists are proponents of vision screening. I believe this is primarily due to low PPV.
PPV is "positive predictive value" a measure of validity of a screening modality(1). PPV is the percent of referred cases that are found to be true for the condition sought(2).
Sensitivity and Specificity are important measures of any screening device(3) but are less important to community acceptance of screening than PPV. They are also impacted differently than PPV by the prescreening prevalence of disease in the screened or studied population. Community pediatricians and the eye doctors who do confirmatory exams are impressed when 3 out of 4 of every screened referrals has a significant, treatable eye disorder. On the other hand, a screening modality with fairly high sensitivity and specificity, but with a PPV less than 50% will become discouraged with the test. The PPV for Alaska Blind Child Discovery is about 89%.
Pediatric ophthalmologists whose practices are already busy with complex disorders will be discouraged with any screening modality that has PPV less than 50% unless they have an efficient, cost-effective method for confirmatory exams (like David Granet’s system of EyeDx plus immediate, low-cost local exams for referrals(4)).
When not performed carefully, even our old standard acuity testing has the potential to have a dismal PPV(5)!
America will be better off if we can get valid vision screening to a high percent of kids Kindergarten age or younger. The Federal P4P program has the potential to move us in that direction. In the process, we need valid local screening. In amblyopia screening, we should strive to find methods with high PPV6, or implement cost-effective efficient confirmatory exams for valid screening methods with lower PPV.
Robert Arnold, MD
Vision Screen Committee Chair
1. Ottar WL, Scott WE, Holgado
SI. Photoscreening for amblyogenic factors. J Pediatr Ophthalmol Strabismus.
1995;32:289-295.
2. Donahue S, Arnold R, Ruben JB. Preschool vision screening: What should
we be detecting and how should we report it? Uniform guidelines for reporting
results from studies of preschool vision screening. J AAPOS. 2003;7(5):314-315.
3. VIPS. Comparison of preschool vision screening tests as administered
by licensed eye care professionals in the vision in preschoolers study.
Ophthalmology. Apr 2004;111(4):637-650.
4. Donahue SP, Arnold RW, Granet D, Wagner R. Pediatric Photoscreening:
Eye to Eye. J Pediatr Ophthalmol Strabismus. Mar-Apr 2004;41(2):72-76.
5. Salcido AA, Bradley J, Donahue SP. Predictive value of photoscreening
and traditional screening of preschool children. J Aapos. Apr 2005;9(2):114-120.
6. Simons K. Amblyopia characterization, treatment and
prophylaxis. Surv Ophthalmol. 2005;50(2):123-166.
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Vision Screening
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