The paediatric otological caseload resulting from improved screening in the first year of life

Selecting infants with OM that need referral and further assessment: creating a case-finding instrument

OBJECTIVE

In the Netherlands, many children are surgically treated for OM. Recent publications question the need for surgical treatment in common uncomplicated OM, although there is certainly a subgroup of infants that do need further assessment and possible treatment. The present study explores the possibility of using known and presumed risk factors for OM as an instrument for selecting and routing an infant with OM to further care.

METHODS

Two questionnaires were used. A questionnaire embracing a wide range of OM-related factors was sent to 6531 children aged nine months that were routinely invited for the hearing screen at nine months. In a second stage, a structured history questionnaire regarding ear and/or hearing problems, subsequent referral and/or treatment, was sent to all parents of children at age 21 months, responding to the first questionnaire. Univariate analysis was performed for identification of potential predictors for surgical treatment of OM for the whole sample as well as for 4 different subsets. Multivariable regression analysis with stepwise backward deletion was applied to arrive at a model for optimal prediction of tube insertion. A ROC (receiver operating characteristic) curve and the accompanying sensitivity and specificity values were analyzed to determine cut off values.

RESULTS

Univariate analysis found 10 items predicting surgical treatment for OM. Multivariable regression analysis resulted in a model with a ROC curve having an area of 0.801 and estimated coefficients for risk factors which were used to calculate a OM-score for each case.

CONCLUSION

The developed scoring sheet, e.g., to be used in combination with physical examinations and/or tympanometry looks promising as a predictor for those children that might benefit from further assessment and eventually surgically treatment for OM.

Air-conduction estimated from tympanometry (ACET): 2. The use of hearing level-ACET discrepancy (HAD) to determine appropriate use of bone-conduction tests in identifying permanent and mixed impairments

OBJECTIVE

The caseload at secondary care in paediatric otology is largely otitis media with effusion (OME) and highly recurrent acute otitis media (RAOM). Few of these cases merit suspicion for hearing loss beyond the middle ear. The companion paper showed that the air conduction estimated from tympanometry (ACET) formula, derived on a very large clinical sample referred for ear or hearing problems and pre-assessed for a clinical trial, gives usable although only approximate estimates for hearing level (HL) on such a caseload. Tympanometry corresponds to a conductive loss (i.e. air-bone gap) so the HL-ACET discrepancy (HAD) should approximate the bone-conduction (BC) threshold. Clinical criteria might enable HAD to substitute for BC tests where those are infeasible, or to identify those most needing BC tests.

METHOD

ACET had been derived for the 4-frequency binaural average on 3085 cases with tympanometry and air-conduction HL available. On the 2701 of those with BC data at 1kHz, we re-calculated ACET for 1kHz only, and then explored the sensitivity/specificity trade of the discrepancy (HAD) in detecting clinically significant BC levels and the correlation between these measures. We further illustrated the generalization of the formula and cut-off on a small separate retrospective clinical sample.

RESULTS

Correlations were moderate in the clinically relevant region. There were five cases of BC> or =30dB in the database. At a HAD cut-off of +5dB, the sift would identify all (nominal 100% sensitivity). For marginal cases, two definitions were adopted (BC> or =25dB and > or =20dB; 9 and 23 cases, respectively). Sift sensitivity remained high (89% and 83%, respectively), and specificity was acceptable (75% for both definitions).

CONCLUSIONS

Given tympanometry and air-conduction HL, comparison of HAD with a recommended cut-off gives acceptable sensitivity and specificity for non-OME hearing problems. BC testing can be reserved for probable positive cases, provisionally only 25% of caseload. HAD could temporarily substitute for BC measurement in children too young to accept bone-conduction transducers in awake testing. Where a high proportion of the caseload is expected to have middle ear fluid, ACET and HAD together offer efficient possibilities for best use of available information.

Epidemiology of permanent childhood hearing impairment in Trent Region, 1985-1993

This retrospective study of permanent childhood hearing impairment (PCHI) > or = 40 dB HL in children born between 1985 and 1993 and resident in Trent Health Region, achieved an ascertainment of 92.9% of that expected from previous studies and 100% for the subset of children born between 1985 and 1990. The prevalence rate of all permanent hearing impairment > or = 40 dB HL for the birth cohort 1985-90 is 133 (95% confidence interval, (ci) 122-145) per 100,000 live births (1 in 750). Sixteen per cent of PCHI were postnatally acquired, late-onset or progressive impairments. Excluding these, the prevalence rate for congenital impairments is 112 (ci 101-123) per 100,000 (1 in 900). The rate for profound impairments > or = 95 dB HL is 24 (ci 20-30) per 100,000 live births (1 in 4150). Prevalence was increased sixfold for children with a history of neonatal intensive care and 14-fold for children with a family history, compared with children with no risk factors. A more than two-fold increase in prevalence was seen in Asian children. For the congenitally-impaired children born between 1985 and 1990, 29% had a stay in neonatal intensive care > or = 48 hours, 30% had a family history of permanent childhood hearing impairment, and 12% had a cranio-facial abnormality (CFA). Over 59% were potentially detectable by a targeted neonatal screening programme using these three high-risk factors. For 1985-1993, the overall yield of the targeted neonatal screening programmes available in three of the 11 health districts was 15% but increased over time. The overall yield from the Health Visitor distraction test was 30% but lower in districts with neonatal screening programmes. Only 59% of children had a stated aetiology, classified by time of onset into genetic, including syndromes and CFA (41%), pre- or peri-natal (10%), post-natally acquired (6%), and uncertain onset (2%). Just under 40% of the children were said to have another clinical or developmental problem, about half of whom had at least two additional problems. The median age at referral, confirmation of the impairment, prescription of the hearing aid and fitting of the hearing aid were, respectively, 10.4 months, 18.1 months, 24.4 months and 26.3 months. A more severe impairment was associated with earlier age. Small improvements in the median age of hearing aid prescription and fitting were seen over time. Twenty-five per cent of children were referred for genetic counselling, the proportion increasing systematically with the severity of the impairment. Based on evidence of the yield from hearing screens we suggest a wider implementation of neonatal screening and further consideration of the role of the health visitor distraction test in the identification of children with PCHI. To facilitate further assessment of services for hearing-impaired children we suggest implementation of a co-ordinated shared list of children with permanent hearing impairment on a region-wide basis to provide adequate numbers for comparison over time, and the routine collection of a minimum set of data for each child.

Changing performance of the Health Visitor Distraction Test when targeted neonatal screening is introduced into a health district

The change in the performance of the HVDT as targeted neonatal hearing screening has been introduced has been examined for the Nottingham district. The records for all children born in the period 1984-1993 within the district and having a permanent hearing loss of > or = 50 dB in the better ear have been examined. The referral route leading to ascertainment of the hearing loss as well as the result of any screening tests were noted. The data shows an increase in the number referred prior to the HVDT, mainly as a result of neonatal screen failure. At the same time there has been a reduction in the sensitivity of the HVDT from 78% in the first half of the decade to 38% for the second half. There are also some indications of an increase in the coverage and the failure rate over the time. Possible reasons for these changes are discussed.

Maternal blood group in otitis media with effusion

Risk factors for otitis media with effusion (OME) have proved difficult to apply in selecting persistent cases, or those otherwise requiring intervention. Explanations may include low predictive values of individual factors and the costs of data collection. In this study, profiles on 225 children from conception to age 7 years were compiled from medical and Health Authority records and structured interviews with parents. On the grounds that nearly all cases receiving medical intervention after waiting and onward referral are more than transitory (although many persistent cases will not receive such attention) this was taken as the dependent variable--a marker of persistence. Established risk factors and maternal blood group A were considered singly to predict intervention, then in combination using logistic regression. Maternal blood group A gave a relative risk (RR) for intervention of 2.82. The noted occurrence of an attack of acute otitis media (AOM) before the first birthday gave a RR of 6.13. When these two factors were used together, the RR climbed steeply to 26.77. These findings suggest that further research is justified into the nature of the influence of blood group A on OME, and the use of combinations of risk factors to give enhanced prediction.

A discussion of current sound field calibration procedures

Calibration of sound fields is an area which has caused much confusion and about which there is some uncertainty. Appropriate calibration is essential if hearing results are to accurately represent the hearing status of a patient, and such results significantly affect the management of many patients. This paper outlines the basis of calibration procedures with respect to sound fields, reviews the recent work in this area, and puts forward the options open to audiologists. The issue of using the dB(A) scale rather than attempting to calibrate in dB HL is discussed and recommendations are made.