Effectiveness of screening for amblyopia and other eye disorders in a prospective birth cohort study.

OBJECTIVE: To establish whether the current vision screening practice in the Netherlands is effective in preventing permanent visual loss and to estimate the sensitivity of the programme. SETTINGS: In the Netherlands, all children are invited for preverbal (1, 3, 6-9 and 14-24 months) and preschool (36, 45, and 60-72 months) vision screening. Screening attendance is high, but the effectiveness in reducing amblyopia is unknown. METHODS: In a 7-year cohort study, 4624 children born in the city of Rotterdam between 16 September 1996 and 15 May 1997 were followed through all routine vision screening examinations. At age seven, visual acuity (VA) of children still living in Rotterdam was assessed by study orthoptists. In case of VA > 0.1 logMAR in one or both eyes, two or more logMAR lines of interocular difference or eye disorders like strabismus, children underwent a more intensive eye examination. RESULTS: Attendance at the 9-month screening was 89%, decreasing to about 75% at later examinations. Of preverbal tests, 2.5% were positive, and of preschool tests, 10%. In total, 19% of children had a positive vision screening test at least once. Amblyopia prevalence was 3.4%. Sensitivity of the vision screening programme was 73% and specificity 83%. At age seven, 0.7-1.2% (confirmed vs final exam) of the children had a VA > 0.3 logMAR in the worse eye compared with 2-3.9% (in literature) reported prevalence in non-screening situations. Children who were less frequently screened had a higher chance of poor vision (>0.3 logMAR) at age seven. CONCLUSION: The Dutch child vision screening programme may reduce the risk of persistent amblyopia (VA > 0.3 logMAR) at age seven by more than half.

Determinants and outcome of unsuccessful referral after positive screening in a large birth-cohort study of population-based vision screening.

PURPOSE: The efficacy of population-based vision screening is hampered by unsuccessful referral after a positive screening test. We studied the nature and causes of unsuccessful referral in a 7-year birth cohort study of vision screening in Rotterdam, the Netherlands. METHODS: All parents of children who had been unsuccessfully referred were asked whether they recalled the referral. Reasons for noncompliance, if any, were identified using semi-structured interviews. Screening records were checked for written evidence of the referral. The parents' fluency in Dutch and their socioeconomic status were also assessed. RESULTS: Of the 561 screen-positive children, 129 (23%) had not been referred successfully. For the current study, 97 parents were successfully contacted. Of these, 14 parents had been willingly noncompliant and 83 said they were unaware of the referral, with 47% having poor to moderate fluency in Dutch. In 53 cases, the screening charts contained no written evidence of any referral. Amblyopia was identified in 3 of the unsuccessful referrals. CONCLUSIONS: In this population-based screening program, 1 of 4 positively screened children was not successfully referred. Apart from parental noncompliance, the unsuccessful referrals can be explained by miscommunication, deficient documentation, and physician noncompliance with screening guidelines. An effective monitoring feedback system may improve the efficacy of child vision screening.

Rotterdam AMblyopia screening effectiveness study: detection and causes of amblyopia in a large birth cohort.

PURPOSE. The Dutch population-based child health monitoring program includes regular preverbal (age range, 1-24 months) and preschool (age range, 36-72 months) vision screening. This study is on the contribution of an organized vision screening program to the detection of amblyopia. METHODS. A 7-year birth cohort study of 4624 children was started in 1996/1997 in Rotterdam. Vision screening data were obtained from the child screening centers. Treating orthoptists working at the regional ophthalmology departments provided information about diagnosis and treatment. The diagnosis was reviewed by two experts. The parents provided additional information on their child's eye history through written questionnaires and telephone interviews. At age 7 years, the children underwent a final examination by the study orthoptists. RESULTS. Of the 3897 children still living in Rotterdam by 2004, 2964 (76.1%) underwent the final examination. Amblyopia was diagnosed in 100 (3.4%) of these (95% CI, 2.7-4.0). At age 7, 23% had visual acuity >0.3 logMAR. Amblyopia was caused by refractive error (n = 42), strabismus (n = 19), combined-mechanism (n = 30), deprivation (n = 7), or unknown (n = 2). Eighty-three amblyopia cases had been detected before age 7. Amblyopia detection followed positive results in vision screening in 56 children, either preverbal (n = 15) or preschool (n = 41). Twenty-six other amblyopes were self-referred (n = 12, before a first positive screening test), especially strabismic or combined-mechanism amblyopia; data were uncertain for one other positively screened amblyopic child. Amblyopia remained undetected until age 7 due to unsuccessful referral (n = 4, three with visual acuity >0.3 logMAR at age 7) or false-negative screening (n = 13). CONCLUSIONS. Most cases of amblyopia were detected by vision screening with visual acuity measurement. Preverbal screening contributed little to the detection of refractive amblyopia.

Reliability and validity of the short form of the child health questionnaire for parents (CHQ-PF28) in large random school based and general population samples.

STUDY OBJECTIVES: This study assessed the feasibility, reliability, and validity of the 28 item short child health questionnaire parent form (CHQ-PF28) containing the same 13 scales, but only a subset of the items in the widely used 50 item CHQ-PF50. DESIGN: Questionnaires were sent to a random regional sample of 2040 parents of schoolchildren (4-13 years); in a random subgroup test-retest reliability was assessed (n = 234). Additionally, the study assessed CHQ-PF28 score distributions and internal consistencies in a nationwide general population sample of (parents of) children aged 4-11 (n = 2474) from Statistics Netherlands. MAIN RESULTS: Response was 70%. In the school and general population samples seven scales showed ceiling effects. Both CHQ summary measures and one multi-item scale showed adequate internal consistency in both samples (Cronbach's alpha>0.70). One summary measure and one scale showed excellent test-retest reliability (intraclass correlation coefficient >0.70); seven scales showed moderate test-retest reliability (intraclass correlation coefficient 0.50-0.70). The CHQ could discriminate between a subgroup with no parent reported chronic conditions (n = 954) and subgroups with asthma (n = 134), frequent headaches (n = 42), and with problems with hearing (n = 38) (Cohen's effect sizes 0.12-0.92; p<0.05 for 39 of 42 comparisons). CONCLUSIONS: This study showed that the CHQ-PF28 resulted in score distributions, and discriminative validity that are comparable to its longer counterpart, but that the internal consistency of most individual scales was low. In community health applications, the CHQ-PF28 may be an acceptable alternative for the longer CHQ-PF50 if the summary measures suffice and reliable estimates of each separate CHQ scale are not required.

Feasibility and reliability of a mailed questionnaire to obtain visual analogue scale valuations for health states defined by the Health Utilities Index Mark 3.

To establish the generalizability (external validity) of the Health Utilities Index Mark 3 (HUI3) as a single-summary score generic outcome measure in numerous countries/subgroups (including children), repeated studies of community preferences should be performed in various settings. In performing multiple HUI3 studies, a mailed questionnaire approach, if feasible and reliable, might be substituted for oral interviews. In the present study, we assessed the feasibility and reliability of a mailed questionnaire approach originally developed for the EQ-5D, for the purpose of collecting Visual Analogue Scale (VAS) valuations from parents as surrogate responders for 65 pediatric HUI3 health states and for the state of being dead. Untransformed mean VAS scores of the health states and scores converted into preliminary Standard Gamble (SG)-utilities were compared with Canadian and French multiattribute utility estimates. A random sample of 1920 parents of schoolchildren (aged 4 to 13) received a mailed questionnaire. Each parent was asked to rate 6 HUI3 health states on a 0 to 100 VAS. Response was 70%. Mean completion time was 20 minutes (SD 9). The questionnaire was rated difficult by only 9%. The current format was, however, inappropriate for valuing the state of being dead. Interrater reliability of health state valuations was.87. Spearman's rank correlations, Pearson-R correlations and intra class correlation coefficients (ICCs) between untransformed VAS valuations and Canadian/French utility estimates were > or =.87. However, preliminary SG-utilities showed diminished ICCs (.71 to.72). The data support the feasibility and reliability of mailed HUI3 valuation questionnaires to a considerable extent, but further methodological studies regarding other formats and different populations are recommended.