Is COPD associated with alterations in hearing? A systematic review and meta-analysis

Abstract

Background and aims: COPD is an irreversible or persistent airflow obstruction, which affects up to 600 million people globally. The primary purpose of this systematic review was to explore the COPD-based alteration in the auditory system function by conducting a quantitative analysis of presently published data.

Materials and methods: We systematically searched seven diverse electronic databases and manual searching of references to identify relevant studies. Data from the selected studies were rated by two investigators independently in a blinded fashion. Meta-analysis was done on pooled data using Cochrane's Review Manager 5.3.

Results: Sixteen articles received suitable scores and were thus included for further processes. Hearing loss (HL) was defined as a change in pure tone audiometry (PTA) thresholds, auditory brainstem response (ABR), and auditory P300 parameters. ABR wave was significantly elongated in patients with COPD than in controls (standardized mean difference [SMD]=0.27, 95% CI: 0.05-0.48, P=0.02). PTA was significantly higher in patients with COPD when compared with controls (SMD=1.76, 95% CI: 0.43-3.08, P=0.0004). We found that patients with COPD had a significantly higher latency than controls (SMD=1.30, 95% CI: 0.79-1.80, P=0.0001).

Conclusion: COPD patients had considerably greater incidence of HL when compared with controls. Interestingly, although the mean PTA thresholds at every frequency for COPD patients were higher than those for controls, these values were still in the slight to mild HL ranges. Prolonged ABR wave latencies in the COPD patients suggest retro-cochlear involvement. Thus, COPD most frequently clusters with HL, but it is worth noting that alteration in hearing is not always recognized by medical experts as a frequent comorbidity associated with COPD.

Keywords: COPD; hearing loss; meta-analysis; systematic review.

Figure 1

Flow diagram for study selection of studies looking at the effects of COPD on hearing function.

Figure 2

Forest plots of SMD for ABR waves’ latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 3

Forest plots of SMD for ABR waves’ interpeak latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 4

Forest plots of SMD for ABR waves’ latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 4

Forest plots of SMD for ABR waves’ latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 5

Forest plots of SMD for ABR waves’ interpeak latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 6

Forest plots of SMD for ABR waves’ latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 7

Forest plots of SMD for ABR waves’ interpeak latencies for both COPD patients and controls. Notes: Bars and diamonds indicate 95% CI. The weights of each study in the meta-analysis are indicated. Analysis model was random effect considering high heterogeneity; effect measure was SMD. Abbreviations: ABR, auditory brainstem-evoked responses; df, degrees of freedom; IV, inverse variance; SMD, standardized mean difference.

Figure 8

Forest plots of studies showing overall SMD for PTA thresholds in patients with COPD and controls at various frequencies. Notes: Bars and diamonds indicate 95% CIs. The weights of each study in the meta-analysis are indicated. Analysis model, random effect; effect measure is mean difference. Abbreviations: df, degrees of freedom; IV, inverse variance; PTA, pure tone audiometry; SMD, standardized mean difference.

Figure 9

Forest plots of studies showing overall SMD for PTA thresholds in patients with COPD and controls at 500, 1,000, 4,000, 6,000, and 8,000 Hz. Bars and diamonds indicate 95% CIs. Notes: The weights of each study in the meta-analysis are indicated. Analysis model, random effect; effect measure is mean difference. Abbreviations: df, degrees of freedom; IV, inverse variance; PTA, pure tone audiometry; SMD, standardized mean difference.

Figure 10

Comparison of P300 latency between COPD and control groups. Abbreviation: df, degrees of freedom.