As per the WHO by 2050 nearly 2.5 billion individuals are projected to possess a point of hearing loss and a minimum of 700 million will need rehabilitation.[1] The prevalence of age-related hearing loss (ARHL) rises steeply with age, from 3% among adults 20–29 years, to 45% of adults 60–69 years, to above 80% in people over 80 years.[2],[3] The prevalence of ARHL and Central Auditory Processing Disorder in a population older than 65 years was 64.1 and 14.3%, respectively.[4] ARHL is the third most typical health condition poignant older adults once heart disease and arthritis.[5]

Hearing impairment cannot be seen and thence its effects are not visible to others, therefore deaf suffers in silence.[6] Early identification of hearing disorders and ear diseases is vital to effective management. The major treatment for mild to moderate hearing loss is the provision of hearing aids.[7] Hearing aids are in market as behind-the-ear, in-the-ear, and in-the-canal models.[8] Despite several well-documented advantages, solely 25% of eligible patients acquire hearing aids and up to 30% of these do not use their aids.[9] The most important barrier is that the perception that hearing loss does not improve despite the amount of loss.[10] Health-care professionals will play a big role in promoting the correct use of hearing aids.[10],[11] Other assistive listening devices ought to be thought about in patients with hearing loss who are unable to use hearing aids.[12] Those that do not tolerate hearing aids, middle ear implants might offer comparable improvement in sound quality and clarity to hearing aids.[13]

The hearing loss ends up in speech perception and communication difficulties that in adult's results in social withdrawal, depression, employment issues, an augmented risk of dementia, and reduced quality of life.[14],[15] The provision of hearing aids is the main clinical intervention for adults with hearing impairment.[16] Other components of aural rehabilitation include directions on the use of hearing aids and communication methods, guidance to reinforce participation in everyday life, and techniques to reinforce speech perception, such as auditory training.[17] Despite proof that hearing aids are effective in providing hearing-specific advantages and improved quality of life,[14],[18] a big proportion of hearing aid users, between 4.5% and 24%, do not wear them,[19] and others wear them only for some time.[20] Reasons for this are comfort and maintenance of hearing aids, psychosocial and situational influences, and device factors.[19] Moreover, expectations of first-time hearing aid users are usually set too high, resulting in unrealistic expectations.[21],[22] The provision of high-quality data by audiologists to hearing aid users, notably those using them for the first time, may help to address many of the above issues. Typically, most of the information offered in a clinical setting is delivered verbally, with the result that many patients forget the information given to them.[23] Between 40% and 80% of information was forgotten after the clinic appointment.[24] For hearing aid users, 25% of information delivered at the hearing aid fitting appointment was forgotten 1 month later.[25] However, a study using a free recall method, reported that half of the information given was forgotten 6 weeks later,[26] with poorer retention of psychosocial issues (35%) compared with practical issues (65%). Although delivery of high-quality written information is recognized and recommended nearly as good as clinical practice.[23] A study used the web as a medium for providing directions to folks with hearing aids, found vital enhancements in the Hearing Handicap Inventory, and also effects were maintained at the 6-month follow-up. This study provides preliminary proof that the Internet is accustomed to delivering education to experienced hearing aid users who report residual hearing problems and their issues are reduced by the intervention.

In addition, to the amplification provided by the hearing aids, factors such as expectations, hearing aid benefit, overall satisfaction, temperament, perceived residual activity limitation, and participation restriction could influence the success of hearing aids.[27],[28] It is vital for hearing aid candidates possess a minimum understanding of the rehabilitation method if they are to benefit from the intervention. It is argued that hearing aid candidates subjected to prefitting visits established a personal relationship with the dispenser that made them more relaxed, reduced anxiety, and co-jointly increased their receptivity.[29] Most rehabilitation research has been conducted after or during hearing aid fitting, however, few studies have investigated the effect of an intervention that preceded standard hearing aid fitting.[30],[31],[32] In a study by Brooks, the prefitting intervention consisted of a home visit performed by professionals from the clinic with the aim of discussing issues and intensifying motivation. Hearing aid fitting was then followed by in-depth follow-up visits for counseling. The treatment cluster showed vital enhancements 8–10 months' posthearing aid fitting in terms of augmented hearing aid use. In addition, a reduction in social hearing handicap compared to baseline was shown.[31] In another study, the results of the intervention were assessed 3 months' postfitting, and no differences were found in hearing aid use, on satisfaction between treatment and control groups.[32]

Hence, the aim of the meta-analysis was to assess the effect of any type of hearing aid interventions on hearing handicap inventory for elderly (HHIE) scores among elders with bilateral hearing impairment in randomized controlled trials (RCTs).

We had used Preferred Reporting Items for Systematic reviews and Meta-analysis (PRISMA) 2020 [Figure 1] guideline to assess the effect of hearing aids on HHIE scores among elders with hearing impairment.

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Data sourcing and selection criteria

Two independent reviewers searched on full-text RCTs for this meta-analysis from worldwide online databases named PubMed and Google Scholar. Studies from January 2000 to January 2022 in the English language conducted among human. Search strategy contains PICO format into it where P-elderly patients with bilateral hearing impairment, I-hearing aid interventions, C-placebo, O-HHIE scores as outcome measures. The Medical Subject Headings terms used were population, population - “elderly with bilateral hearing impairment” “hearing loss,” along with intervention - “hearing aid interventions,” “hearing rehabilitation programme,” control - “placebo,” “passive placebo,” “over the counter,” outcome-“HHIE scores,” “HHIE-E score,” “HHIE-S score.”

Study selection

Two reviewers independently screened for published trials for their titles, and abstracts. RCTs were taken as research design from January 1, 2000, to January 1, 2022, in the English language conducted among human. The study participants include elders, aged >60 years with bilateral hearing impairment and using any type of hearing aids or undergone any hearing rehabilitation program were included in the study. The exclusion criteria will be elderly patients will unilateral hearing loss and not prescribed with any hearing aids. The tool used for measuring outcome was HHIE. This instrument contains 25 items and generates two subscales; 13 questions are designed to detect the emotional consequences of being a hearing-aid user (HHIE-emotional [HHIE-E]), and 12 questions are designed to detect the social and situational consequences of being a hearing-aid user (HHIE -social/situational [HHIE-S]). For each item, there are three potential responses: yes (4 points), sometimes (2), or no (0). A higher score corresponds to greater perceived activity limitation and participation restriction.

Outcome measures

Both independent reviewers explored the main outcome to assess the effect of hearing aids on HHIE total score and subgroups of HHIE as HHIE-S, HHIE-E were explored.

Data extraction

Two independent authors had completed the data extraction from selected RCTs. Any disagreements in eligibility for inclusion were resolved by discussions among authors formally. After selection of each trial, information extracted was tabulated in the form of the author's name and year of publication, the number of participants, experimental and control group, mean age, percentage of male participants, treatment for an interventional group, control group, and follow-up period. All references of the included trials were searched for further selection.

Assessment of risk bias and quality assessment

The Cochrane risk-of-bias assessment tool guidelines by Higgins et al.[33] used. The risk of bias for each selected RCTs includes selection, performance, detection, attrition, reporting, and other bias [Figure 2]a and [Figure 2]b. All studies were denoted in the form of low, high and unclear risk for each component. Any dissimilarities in the opinion of two independent reviewers solved by mutual consensus among them. Randomization and reported for generating a randomized sequence method were properly described among all eight trials. Allocation concealment was properly described between two trials[34],[35] whereas it was unclear in the other six trials.[36],[37],[38],[39],[40],[41] Blinding of participants and researcher was only explained in four trials.[37],[38],[40],[41] Blinding of outcome assessors was unclear among all eight trials. Data were well described among two trials,[38],[40] whereas five trials showed unclarity in completion of data. All eight trials well described the data, hence no selective reporting bias was found. All eight trials did not contain any other biasness in the study data.

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Data analysis

Complete data derived from included trials are tabulated in [Table 1]. Final statistical analysis was performed according to the protocol in the latest edition of the Cochrane Handbook for Systematic Review of RCT, and RevMan Manager version 5.4 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen) was used.

Continuous data of HHIE, HHIE-S, HHIE-E outcomes in the form of mean and standard deviation with 95% confidence interval (CI). Heterogeneity assessed by I2 statistics of treatment effects among selected trials assessed with Chi-square test. We categorized I2 of 0% with no heterogeneity, 50% with minimal heterogeneity, more than 50% was substantial heterogeneity. We used a fixed-effect model for the final meta-analysis with a significant P = 0.05 and an I2 statistic ≤50% (in forest plot suggestive of heterogeneity) and random effect model if I2 statistic >50%. All P values were two-sided with statistically significant at ≤0.05. The potential publication bias was assessed by plotting the funnel graph for the mean and standard deviation. Sensitivity analysis was also performed to assess each particular RCTs' influence and excluding the trials with the enormous effect that causing heterogeneity in the final result one by one. Planned stratified analysis was performed based upon subgroups of HHIE as HHIE-S and HHIE-E.

Study selection and their characteristics

First, trials were searched as per 2020 guidelines of PRISMA flow diagram that reported, screened, excluded, and finally included. Twenty-eight trials were identified after searching through databases [Figure 1].

Detailed characteristics of the all 8 trials are shown in [Table 1]. Total 445 (214/231 in interventional group/control group respectively) participants were included in this study for final analysis. Eight trials had matched eligibility criteria but after performing sensitivity analysis only seven trials were shown in forest plot for final analysis for the main outcome of HHIE score. However, 6 trials were found eligible for stratified analysis of HHIE-S, HHIE-E but after performing sensitivity analysis, 2 trials were not showing any heterogeneity.

[Table 2] shows sensitivity analysis of main outcome HHIE scores which includes omitting a single trial done by Lundberg et al., in 2011[40] showing significant heterogeneity (I2 63%, P = 0.0009) mean difference (MD), CI (−3.08 (95% [CI −5.00 to –1.16]) and no significant difference between the interventional and control groups (P = 0.06) with random effect model. Hence, seven trials were included in the study and heterogeneity got reduced (I2 = 48%, P = 0.07) with significant improvement in MD (CI) of HHIE scores found in interventional group as compared to control group (−2.21 [95% CI = −4.24 to −0.19], P = 0.03) with fixed effect model.

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The findings of the main outcome-hearing handicap inventory for elderly score

Pooled analysis was done on seven trials[34],[35],[36],[37],[38],[39],[41] which showed significant reduction in mean score of HHIE among active interventional group (hearing aid) as compared to control group (placebo) with MD and CI (−2.21 [95% CI = −4.24 to −0.19]), P = 0.03. Total participants were 375 and 181 in the interventional group whereas 195 in the control group. Overall heterogeneity found using fixed effect model (I2 = 48%, P = 0.07) in this pooled analysis [Figure 3].

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Stratified analysis of hearing handicap inventory for elderly-social/situational and hearing handicap inventory for elderly-emotional outcomes

A stratified analysis was done among 6 trials but heterogeneity statistic was high and hence, only two trials.[37],[40] were included in this analysis. Subgroups of HHIE as HHIE-S and HHIE-E scores and both groups showed no significant difference between the subgroups (I2 = 0%, P = 0.97) for the reduction in MD of scores −5.34 (95% CI −7.05 to −3.64] as shown in [Figure 4].

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Sensitivity analysis for stratified analysis

In [Table 3] which shows the sensitivity analysis of HHIE-S and HHIE-E scores, outcome includes omitting of four trials, one by one from this stratified analysis. Omitting trial done by Malmberg et al., in 2016[34] showed significant heterogeneity (I2 = 69%, P = 0.04) with MD, 95% CI (−3.68 [−5.57, −1.79]). Similarly, another trial done by Marie et al., 2009[39] showed significant heterogeneity (I2 = 71%, P = 0.03) with MD, 95% CI (−3.71 [−5.63, −1.79]). Consecutively, a trial done by Marie et al., 2009 showed significant heterogeneity (I2 = 62%, P = 0.07) with MD, 95% CI [−4.23 [−6.30, −2.16]). At the last trial done by Elisabet et al., 2014[37] showed significant heterogeneity (I2 = 83%, P = 0.002) with MD, 95% CI (−2.42 [−3.98, −0.86]). Hence, these four trials were done by Malmberg et al., in 2016,[34] Marie et al., in 2009,[39] Marie et al., in 2009[38] and Thorén et al., in 2011[36] were excluded and only two trials done by Thorén et al., in 2014[37] and Lundberg et al., in 2011,[40] included found suitable for the pooled subgroup analysis of HHIE.

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The findings of the current meta-analysis discovered that hearing aid interventions considerably tested effective in reducing HHIE score among elders with bilateral hearing impairment by employing a fixed-effect model with P = 0.03. These findings were supported by previous trials. A study was conducted to analyze the impact of prefitting user-controlled hearing aid adjustments. The prefitting intervention group showed positive effects.[41]

Another study was conducted on the employment of web (online education) within the audiological rehabilitation method to tell and guide hearing aid users regarding communication methods, hearing ways, and the way to handle hearing aids. The study concluded that (online education) web can be used to deliver education to experienced hearing aid users who report residual hearing loss.[40]

Strength of the study

This meta-analysis includes only RCTs that exclude the majority of confounding variables which may affect study results. Heterogeneity was <50% among included trials which suggest uniformity.

Limitations of the study

We could not have matched the duration of follow-up among all included trials.

This meta-analysis shows moderate quality evidence regarding the use of hearing aids and its effectiveness on the reduction of HHIE score among elders with hearing impairment. Evidence suggested that it is effective in specific elder population and sub-group analysis also done to assess social and emotional consequences due to hearing loss for a better understanding of its effectiveness. Adherence to hearing aid intervention or rehabilitation program is highly recommended by researchers.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.