Relationship between platelet parameters and sudden sensorineural hearing loss: a systematic review and meta-analysis

Hearing impairment and diverse health outcomes : An umbrella review of meta-analyses of observational studies

BACKGROUND

Globally, it is estimated that approximately 1.3 billion people live with some form of hearing impairment. Major causes of hearing loss include infection/disease, age-related factors, and occupational factors. Numerous systematic reviews and meta-analyses have attempted to synthesise literature on these topics. To date there has not been a systematic evaluation of the relationships between hearing impairment and diverse physical, mental, and social outcomes.

OBJECTIVE

We performed an umbrella review of systematic reviews of observational studies with meta-analyses for any physical disease, biomarkers of disease, mental health or cognitive outcomes, and/or modifiable risk factors associated with hearing impairment.

METHODS

For each meta-analytic association, random effects summary effect size, 95% confidence intervals, heterogeneity, evidence for small-study effect, excess significance bias and 95% prediction intervals were calculated, and risk of bias was assessed via the AMSTAR2 tool. These were used to grade significant evidence (p < 0.05) from I to IV, using the recommendations from the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

From 3747 studies, 21 were included covering 54 outcomes. Overall, 44/54 outcomes (82%) yielded significant results. Of the highest quality evidence, age-related hearing loss and non-specific hearing impairment were negatively associated with several types of cognitive impairments; pediatric bilateral hearing loss was negatively associated with quality of life, sensorineural hearing loss was positively associated with rheumatoid arthritis and tinnitus was positively associated with temporomandibular disorders.

CONCLUSION AND RELEVANCE

Results show moderate quality evidence for associations between several types of hearing impairments and cognitive difficulties, quality of life and systemic diseases such as rheumatoid arthritis. Practitioners and public health policies should note these findings when developing relevant healthcare policies.

The prognostic and predictive value of platelet parameters in diabetic and nondiabetic patients with sudden sensorineural hearing loss

BACKGROUND

We aimed to evaluate the association between mean platelet volume, platelet distribution width (PDW), platelet count (PC) and plateletcrit (PCT), and the presence of sudden sensorineural hearing loss (SSNHL) and treatment response. In the literature, there is no study that investigates the platelet functions in diabetic patients with SSNHL.

METHODS

The patients were retrospectively assigned into Group 1 (68 diabetic patients with SSNHL), Group 2 (63 nondiabetic patients with SSNHL) and Group 3 (64 healthy controls).

RESULTS

PC was not significantly different between the groups (p > 0.05). MPV, PDW and PCT values were significantly higher in Group 1 as compared to Groups 2 and 3 (p < 0.05). Platelet parameters were not significantly different between the patients who were responsive and nonresponsive to the treatment. Therefore, the platelet parameters did not affect prognosis significantly in this study samples (p > 0.05).

CONCLUSIONS

This study showed that platelet parameters did not have a significant effect as a prognostic and predictive value in diabetic and nondiabetic patients with SSNHL. Further studies with more homogenous and larger study groups investigating the platelet parameters are needed to demonstrate microvascular damage and vascular alterations induced by diabetes mellitus.

Low-Normal Platelets and Decreasing Platelets Are Risk Factors for Hearing Impairment Development

OBJECTIVE

Identification of undefined risk factors will be crucial for the development of therapeutic strategies in hearing impairment. Platelets are likely to affect the development of sudden sensorineural hearing loss, which is a primary risk factor for permanent hearing impairment. This implies that abnormal platelets might contribute to long-term hearing loss. This study investigated the role of platelets in the development of hearing impairment over a 5-year period.

METHODS

This study was a retrospective cohort study and consisted of a population-based survey, which was performed for 1,897 participants in 2014 to 2019. To evaluate the effect of platelet level on hearing ability, the subjects were divided into two groups: a high-normal platelet group (25 ∼ 40 × 10⁴ cells/μL) and a low-normal platelet group (15 ∼ 25 × 10⁴ cells/μL). Subjects were defined as having hearing impairment when pure tone audiometry was over 25 dB HL in either ear (tested in 2017 and 2019). Incidence of hearing impairment was analyzed.

RESULTS

Incidence of hearing impairment at low frequencies was significantly higher in the low-normal platelet group than in the high-normal group year over year. Low-normal platelet count associated with low-frequency hearing impairment (LFHI) incidence (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.15-4.76). In the low-normal platelet group, subjects whose counts declined from baseline developed more LFHI than those whose counts increased over time. Further, decreasing platelets appeared to be an independent risk factor contributing to the incidence of LFHI (OR, 2.10; 95%CI, 1.09-4.06) in the low-normal platelet group.

CONCLUSION

Both a low-normal platelet and a declining platelet count were independently associated with the incidence of LFHI.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:E1287-E1295, 2021.