Estimating NHS Hearing Aid Uptake in Wales Using AuditBase Rhys Meredith 1, Vinaya K. C. Manchaiah 2 & Dafydd Stephens 3 1 Audiology Department, Singleton Hospital, ABM University Health Board, Swansea SA2 8QA 2 Long Term & Chronic Conditions Centre, College of Human & Health Sciences, Swansea University, Swansea SA2 8PP 3 Department of Psychological Medicine & Neurology, School of Medicine, Cardiff University, Cardiff CF14 4XN Introduction Surveys of hearing aid possession in the population of the UK date back to Wilkins survey conducted prior to the inception of the NHS (Wilkins, 1948) and which gave a Figure of 3.26% of the adult population having hearing aids. Early surveys of the use of NHS hearing aids date back to Gray and Cartwright (1951) and were reviewed by Stephens (1977). Studies carried out between in the 1980s and 1990s reported that about 4% of the adult population in the UK possessed hearing aids and about 3% actually used them (Davis, 1995; Stephens et al 2001) 1. No increase in hearing aid use was observed over this period of time and less than 20% of those reporting hearing difficulties actually possessed a hearing aid. The National Study of Hearing (Davis 1995) demonstrated that the hearing aid uptake in the UK was far lower than the prevalence of moderate bilateral hearing impairment. The data for these studies were mainly obtained from postal questionnaires, and like most epidemiological surveys a representative sample of the population was obtained and the results extrapolated to obtain an overall estimate. The universal adoption of electronic patient management systems in NHS Audiology allows the possibility of an alternative method of estimating hearing aid uptake. The present study aims to identify all relevant cases registered on NHS Audiology databases in Wales as well as the mean age of first time hearing aid fittings. AuditBase is a patient management system that records demand, activity, waiting lists, and patient demographics as well as assessment and management information. The software had originally been designed in Denmark by Auditdata and was used in a limited way by Audiology departments in several Danish Hospitals. Since 2002 each of the thirteen separate audiology departments in Wales has used AuditBase and developed comprehensive databases of patient demographics and activity. Since 1999 Wales has had a devolved Welsh Assembly Government with the NHS in Wales having separate management and separate funding streams from that of England. This was of benefit to a study of hearing aid uptake as very few patients resident in Wales would access their healthcare in England and vice versa. The thirteen Audiology Departments Although there are now only 7 Health Boards, in 2009 there were thirteen independent departments each with its own Audiology database operating in Wales. The departments are based in; Baglan, Bangor, Bodelwyddan, Brecon, Bridgend, Cardiff, Carmarthen, Llantrisant, Merthyr, Newport, Pembrokeshire, Swansea and Wrexham Method Database reporting software (Crystal Reports Version 11.0.0.1282) was used to write a report that could be used to interrogate the contents of each of the 13 separate databases in Wales. Each departmental head of service was requested to run two reports. The first aimed to identify all surviving patients who had accessed an NHS hearing aid, the second was to establish the mean age of patients at the time of their first hearing aid fitting during the calendar year 2008. The reports were run on local databases and the data collected between September and November 2009. To identify patients who had accessed an NHS hearing aid service, each local head of service was requested to search their local databases for patient activity linked to appointment types 1. The Stephens et al paper was published in 2001 but the survey was completed in 1988 and The Davis 1995 data were collected in the early 1980s 17
directly associated with hearing aid provision. The report identified and counted any patient who had any such appointment. However, importantly any patient accessing the service on more than one occasion would only be counted once. Steps were taken to exclude as many children as possible and also those patients who were recorded as being deceased. Section 1: Hearing Aid Uptake Known Sources of Error Total, unrestricted access to each of the separate databases was not possible. It was also known that the Audiology sites had different operating practices and protocols. Therefore the following sources of error were considered; The accuracy of patients coded as deceased. The proportion of patients who appeared to have accessed the hearing aid service but who had never attended any appointments Paediatric hearing aid cases included in adult appointment types Patients accessing hearing aid services in more than one area Results The total number of appointment types reported was 179 with a mean of fourteen appointment types from each department. The thirteen Audiology departments submitted their total adult hearing aid uptake which is shown on Figure 1. Figure 2 Hearing aid uptake compared to the estimated total population served by each individual site. The total number of individuals who were identified by the report as having obtained an NHS hearing aid was 172 000. People who had been coded as deceased were excluded. Mid year population estimates for Wales for 2008 (Office for National Statistics) provide an estimate of the adult population of Wales of 2.44 million people. This gives an initial estimate of hearing aid uptake amongst adults in Wales of 7%. However as previously mentioned there were a number of sources of data error that need to be considered. Some data accuracy checks DNA/Cancelled/Attended Removal of children Some centres had included children which most other centres had not. To establish the magnitude of this effect Swansea data was re-checked in May 2010. By this date the total hearing aid uptake had risen from 15 747 to 16 353 but only 434 of these cases were aged under sixteen years. This is only 2.65% of the hearing aid population and 0.18% of the total population and so can effectively be ignored. Figure 1 Adult Hearing Aid Uptake by individual Audiology department The hearing aid uptake was compared to the estimated population served for each area (total estimated population included children). The number of hearing aid cases correlated well with the reported population served as shown in Figure 2. Private Vs NHS The present study did not seek to include hearing aid use for cases who had not accessed NHS hearing aids. According to Stephens et al (2001), in the UK, 80-85% of people who possess a hearing aid obtained them via the NHS with a further 5% possessing both NHS and private hearing aids. A finding which is in keeping with Stevenson and Dawfrey (1980) and Davis et al (2007). 18
Overestimation due to failure to remove deceased cases The reliability of updating the status of patients when they are deceased is variable between departments. The effect that this variability has on the overall estimate of uptake was unknown. Each department was asked about the reliability and accuracy of their updating procedures. Seven updated irregularly and only when information was made available. Three reported regular manual updates but with the potential for inaccuracy. A further three reported exceptionally high reliability due to regular automated updates from reliable data sources such as the local patient management system. To estimate the reliability of the overall grouped data the proportion of cases that were still present in the databases which should have been re-coded as deceased needed to be estimated. The database at Swansea was infrequently updated therefore the accuracy of updating when patients were deceased was considered to be low. To establish the effect of the error a random sample of cases were analysed. Estimation of the error due to not updating cases when deceased The authors had full access to the database at Swansea which therefore allowed for more detailed analysis of the Swansea data. Ten cases were randomly sampled from each 5 year age group for ages between 40 to105 years, 140 cases in total. All 140 cases were checked against a definitive source which was the local patient management system, As shown in Figure 3, the survival rates for the age groups varied from 100% to 10%. As expected the older the age group the lower the survival rate. Figure 3 Survival rate estimate applied to the original data obtained from the Swansea database The original unadjusted data available for Swansea give an estimated hearing aid takeup of approximately 16 000 cases. However when the data was adjusted for inaccuracy of coding as deceased the estimate was reduced to approximately 12750 cases. Figure 4 Original and adjusted age demographics of the data obtained from the Swansea database As shown in Figure 4, the adjustment to the Swansea data based on the sampling of cases by age group resulted in an overall estimated survival rate of 79.6% of the original total. To test whether this was a reasonable representation of the true Figure it was compared to the survival rate for a centre known to have excellent data accuracy for coding deceased cases. The database at Bodelwyddan is regularly updated by the local patient management system and thus in effect can be regarded as 100% accurate. The local manager was asked to run two hearing aid uptake reports. The first would include all hearing aid cases and the second would exclude any cases coded as deceased. The survival rate was 79% of the total cases. This was almost identical to the estimated survival rate from sampling the Swansea database, thus giving added reliability to the statistic. The final adjusted estimate There were differences in practice and uncertainty regarding the accuracy of individual databases in Wales. Therefore the best estimate for hearing aid uptake is somewhere between the original, unadjusted estimate (i.e. 172 000 cases, 7% of total adult population), and the adjusted estimate which accounts for inaccuracies in updating databases when patients are deceased (i.e.137 000, 5.6% of total adult population). 19
Section 2: Age of hearing aid fitting for new adult patients The second part of our study is concerned with the mean age of fitting of hearing aids to new adult patients. A recent Health Technology Assessment (Davis et al, 2007) stated that the median age of new hearing aid fittings in the UK has risen from 70 years in the early 1980s to 74 years in 1999 (Davis et al, 2000). For the present study responses were obtained from each of the thirteen Welsh Audiology departments. Each selected the appropriate appointment type associated with the patient category of interest. Namely those adult patients attending the audiology clinic to be fitted with a hearing aid for the first time. The age of each patient and the total number of patients attending these appointments was recorded. This study did not have access to individual patient data from most clinics and so only individual mean ages for each site and an overall mean could be calculated. No measures of variance, (i.e. standard deviations, percentiles etc) could be generated for the overall Wales data. audiological data for Wales, there are two factors which would indicate a degree of similarity; 1. The mean age of hearing aid fitting in Swansea was very close to the overall mean age for Wales (Swansea = 69.4 years; Wales = 69.9 years). 2. A detailed age distribution was available for two clinics; Swansea (situated in South West Wales) and Wrexham (situated in North East Wales). As shown in Figure 6 the age distributions for Swansea and Wrexham were very similar. Results The data relates to the calendar year 2008. There were 22,000 new hearing aid fittings in Wales. The mean age of fitting for the individual departments ranged from 67.1 to 73.3 years as shown in Figure 5. The overall Wales mean was 69.9 years. Figure 6 Comparison of age distributions for Swansea and Wrexham first hearing aid fittings Figure 5 Mean age of new hearing aid fittings in the 13 Welsh Audiology Departments The authors had greater access to the Swansea Audiology clinic database. This provided the opportunity for more detailed statistical analysis to be performed on that data. Although the Swansea data may not be representative of the In order to conduct a more detailed analysis of the age distribution, the age of hearing aid fitting in Swansea was gathered for a two year period, the calendar years 2008 and 2009. The total number of cases fitted in that period was 2586 cases and the mean age of hearing aid fitting was 69.7 years. For both Swansea and Wrexham, half of the cases were aged over 72 years and a quarter more than 80 years. There were 1178 males with a mean age of 68.5 years (s.d. 13.6) and 1175 females with a 20
mean age of mean age 71.6 years (s.d. 15.1). The ages were found to be significantly different (t= 5.38, df=2351, p<0.001). Figure 7 presents data of first hearing aid fitting in Swansea at various age groups. Figure 7 Ages of 1st Hearing Aid fittings in Swansea 2008-9 by gender Discussion The structure of the Health Service and Audiological service in Wales allows an opportunity to analyse the uptake and age of hearing aid uptake for the population of the country as a whole rather than by sampling. There are sources of error due to database inaccuracies such as the coding of deceased cases. This resulted in an estimated range of hearing aid uptake of between 5.6-7% of the adult population. The increase in hearing aid uptake has been observed in Welsh Health Surveys, which show a similar estimate to this study (see Figure 8). The estimated uptake of hearing aids found in this study is somewhat higher than studies carried out in the UK in the 1980s and 90s. This may be due in part to an increase in the population age distribution compared to 15-20 years ago. Figure 8: Hearing Aid Uptake in Adults Welsh Health Survey It is also possible that the estimated increase is due to the improvement in the quality and accessibility of hearing aids available from NHS clinics, particularly following the Modernisation of Audiology Services in Wales project (MASW) and the Modernisation of Hearing Aid Services project (MHAS) in England. The mean age of patients accessing a hearing aid for the first time in Wales was 70 years. This is similar to the estimated age quoted by UK studies in the past. It continues to be likely that people obtaining a hearing aid for the first time have lived with a hearing impairment for a significant period. References Davis A. Hearing in Adults. London Whurr: 1995 Davis A, Smith P, Lovell E, Ferguson M, Lutman M, Gatehouse S et al. Adult Hearing Screening; what would be an efficient and effective hearing screen for ability to benefit from amplification? In XXV International Congress of Audiology, The Hague; 2000. P22. Davis A, Smith P, Ferguson M, Stephens D, Gianopoulos I. Acceptability, benefits and costs of early screening for hearing disability: a study of potential screening tests and models. Health Technology Assessment 2007; 11 (42) Gray P G, Cartwright A. The medresco hearing aid its use and value. Lancet 1951; i: 1170. Stephens S D G. Hearing aid use by adults: a survey of surveys. Clinical Otolaryngology 1977; 2: 385-402. Stephens D, Lewis P, Davis A, Gianopoulos I, Vetter N. Hearing aid possession in the population: lessons from a small country. Audiology 2001; 40: 104-111. Stevenson J and Dafrey L, A study of private hearing aid users in London. Br J Audiol 1980; 14:105-114 Welsh Health Survey: http://wales.gov.uk/ topics/statistics/theme/health/healthsurvey/results Wilkins L T. Survey of the prevalence of deafness in the population of England, Scotland and Wales. London, Central Office of Information, 1948. Acknowledgements Thanks to all the Audiology Heads of Service in Wales for assisting with data collection and to Clive Sparkes and Simon Unwin for helpful comments on the design of the database report. 21