Page 117 - DISINVESTMENT AND IMPLEMENTATION OF VISION SCREENING TESTS BASED ON THEIR EFFECTIVENESS
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Effectiveness of routine population-wide orthoptic preschool vision screening tests at age 6-24 months in The Netherlands
Diagnosis and age of detection of amblyopia
After screening at age 6-24 months, from the 173 versus 123 referrals, 44 out of 5560 (0.79%) versus 27 out of 5062 (0.53%) children were diagnosed with amblyopia (RR = 0.67 [95%CI 0.42, 1.09] (Table 3). Other eye disorders were diagnosed in 29 (0.52%) versus 21 (0.41%) children (Table 3 & Appendix).
After VA measurements, of the 598 referrals (out of 5560 children) 120 (2.2%) in the control group (36-60 months) were diagnosed with amblyopia versus 107 (2.1%) out of the 632 referrals (out of 5062 children) in the intervention group (Table 3). Other eye disorders were diagnosed in 31 (0.56%) versus 21 (0.41%) children (Table 3 & Appendix). Amblyopia detected outside screening, for instance, after referral by a GP or after self- referral, yielded 21 (0.38%) versus 25 (0.49%) cases of amblyopia (Table 3), and other eye disorders in 21 (0.38%) versus 32 (0.63%) children (Table 3 & Appendix).
In total, 185 (3.3%) children in the control group and 159 (3.1%) children in the intervention group were diagnosed with amblyopia (p 0.613) as a result of referral by CHC centres, 6-60 months screening and referrals made outside of screening (Table 3, Figure 4). Insufficient data was obtained in 234 (4.2%) in the control group versus 208 (4.1%) children in the intervention group. These children could not be classified as amblyopic because of insufficient or failed VA measurements twice and no available orthoptic data.
Based on the intention to screen analysis, there was no significant difference (p 0.55) between both groups in their time to amblyopia diagnosis. The corresponding HR was 0.98 (95%CI 0.79-1.21). Most amblyopia diagnoses were made after the VA measurements at 36 and 45 months, with no advantage in time to diagnosis by screening performed up to 36 months (Figure 5a). A sensitivity analysis yielded an unchanged absence of a difference between both groups (i.e. no benefit of screening) after multivariate correction for the number of visits (HR adjusted (HRadj) 0.97, 95%CI 0.78-1.20), gender (HRadj 0.98, 95%CI 0.79-1.21) or children identified outside of the study (i.e. referred by general practitioners) (HRadj 0.97, 95%CI 0.78-1.20). The per protocol analysis, comparing those without any preverbal screening (n 2083) with children receiving ≥1 preverbal screening test (n 8539), also showed no significant difference (p 0.11) between both groups in their time to amblyopia diagnosis (HR 0.79, 95%CI 0.59-1.06) (Figure 5b).
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