Hearing loss is a leading cause of disability in older adults and has been identified as a potentially modifiable risk factor for cognitive decline. The healthy hearing for healthy ageing (HAHA) trial aims to test whether a structured rehabilitation approach can improve real-world listening and explore associations with neural and cognitive measures. The protocol highlights gaps in routine care: delayed diagnosis, variable fitting practices, limited systematic follow-up and scarce objective validation of rehabilitative outcomes.
HAHA is a proof-of-concept, single-site, two-arm parallel-group randomised controlled trial with a 12-month intervention period and a 12-month extended follow-up. The trial is embedded within routine clinical services at Kuopio University Hospital (KUH) ENT clinic, preserving real-world workflows including standard clinical wait-times (3–6 months) before the primary HA fitting. The pragmatic design aims to maximise external validity while maintaining trial rigour.
Up to 200 participants aged 65–84 years with mild to moderately severe sensorineural hearing loss are recruited from patients referred for initial hearing aid (HA) rehabilitation. Exclusion criteria include conductive or asymmetrical hearing loss, contraindications to HAs, diagnosed cognitive impairment or cognitive concerns under evaluation, and other health conditions preventing participation. Screening occurs during routine assessment by an ENT specialist; informed consent is obtained by a study nurse at the same appointment. Recruitment commenced 1 October 2024; anticipated primary completion is 29 February 2028.
The active intervention is a clinician-led data-driven hearing rehabilitation (DDHR) programme. DDHR uses structured fitting and verification procedures and the systematic collection of objective outcome measures—such as SPIN tests, HA usage logs and patient-reported outcome measures (PROMs)—to guide rehabilitation decisions according to predefined criteria. The approach is explicitly clinician-implemented and does not include algorithmic or artificial intelligence decision-making.
Standard care reflects the routine KUH model: HAs are fitted using manufacturers’ proprietary algorithms; real-ear measurements (REM) are performed only in clinically judged complex cases, and routine systematic assessment of rehabilitation outcomes is not typically performed. All trial participants receive the same hearing aids as those used in routine care.
Participants are randomised 1:1 using a computer-generated list in blocks of four; sealed envelopes prepared by a biostatistician are used by a study nurse for allocation. Complete double-masking is not feasible because of differences in fitting protocols; however, outcome assessors are masked to group allocation and participants are not actively informed of their allocation. The trial adopts pragmatic procedures aligned with routine clinical care while maintaining masked outcome assessment where possible.
Primary outcome
Secondary outcomes
Exploratory outcomes
Baseline assessments are completed prior to randomisation. Outcome assessments are repeated at 12 and 24 months after the first HA fitting, which marks the intervention start. All outcome assessments are performed by study nurses trained in HAHA procedures and masked to allocation. Audiometry follows international standards using calibrated equipment. Intention-to-treat analyses will include all randomised participants except those who withdraw consent.
Analyses will follow CONSORT guidelines. Randomisation procedures and use of intention-to-treat principles are specified. The protocol includes the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) checklist in supplemental materials. Details on statistical models and handling of missing data are provided in the protocol documentation (supplemental material).
Ethical approval was granted by the Regional Medical Research Ethics Committee of the well-being Services County of North Savo (approval no. 697/2023). The trial is registered (NCT06495268). Findings will be disseminated through peer-reviewed publications, conference presentations and engagement with clinical and patient communities.
Strengths: embedding the trial in routine clinical practice enhances real-world relevance and reduces selection bias; the randomised design, sample size of up to 200 and extended follow-up strengthen the study; a usual-care control arm preserves applicability to real-world settings; masking of outcome assessors reduces measurement bias.
Limitations: complete double-masking is not possible and participant masking may be incomplete due to fitting protocol differences; follow-up may be insufficient to detect substantial cognitive decline or incident dementia, although an extended 24-month follow-up is planned.