Osteoporosis Predisposes to Higher Risk of Sudden Deafness

Becky McCall

April 22, 2015

Patients with osteoporosis had a significantly higher risk of sudden sensorineural hearing loss (SSNHL) than those without osteoporosis, according to the first and largest Asian population-based study to demonstrate a relationship between the two conditions.

Specifically, the increased risk of developing SSNHL in patients with osteoporosis was 1.76 times that of people without the bone disease, indicates the study, published online April 16 in the Journal of Clinical Endocrinology & Metabolism, by Dr Mei-Chen Yeh (Chi Mei Medical Center, Tainan, Taiwan) and colleagues.

Senior author Dr Kai-Jen Tien (Chi Mei Medical Center) said: "Clinicians should not ignore hearing problems in osteoporotic patients. Likewise, patients with osteoporosis should be aware and inform their clinician if they suffer from suspected hearing impairment."

Previous studies that have looked at osteoporosis and its potential association with SSNHL had small sample sizes and cross-sectional designs, and the results were inconclusive, prompting Dr Yeh and colleagues to investigate the relationship further.

After reviewing the literature on the two conditions, there seemed to be a causal relationship, "but the relationship between these two diseases was unclear," Dr Tien told Medscape Medical News.

In addition, he and his colleagues felt motivated to conduct the analysis because they encountered osteoporotic patients who complained of hearing problems during their daily clinical practice.

Analysis of World's Most Complete Population Data Set

Data were drawn from Taiwan's National Health Insurance (NHI) claims database, which covers 98% of Taiwan's residents and as such is one of the largest and most complete population-based data sets in the world, say the researchers.

A retrospective cohort analysis was conducted with two study groups — a new-onset osteoporosis group (n = 10,660), who were diagnosed from 199 to 2008, matched on a 1:3 ratio with a nonosteoporotic control group (n = 31, 980). People were also matched by age, sex, baseline comorbidities (including diabetes mellitus, hypertension, chronic kidney disease, and coronary artery disease), residential area, and monthly income. The vast majority of subjects were female (89.5%) and over 50 years old (91%).

The diagnosis of osteoporosis was made by dual-energy X-ray absorptiometry (DEXA). All patients were tracked until SSNHL was diagnosed, death, or the end of 2011, and the main outcome measure was the identification of patients with newly diagnosed SSNHL by ICD-9CM code.

The incidence rates of SSNHL in patients with osteoporosis and the comparison group were 10.43 and 5.93 per 10,000 person-years, or 91 in 10,660 osteoporotic patients vs 155 in 31,980 nonosteoporotic subjects.

This equates to patients with osteoporosis having almost double the risk of developing SSNHL as patients without osteoporosis (incidence rate ratio [IRR], 1.76; P < .0001).

Age and Gender Associated With SSNHL

Patients with osteoporosis aged 50 years or older were at higher risk of SSNHL than younger patients, with an IRR of 1.50 in those between 50 and 64 years old and even higher, 2.33, in those aged 65 years or older.

Also, women with osteoporosis were found to be at higher risk of SSNHL than those without osteoporosis (IRR, 1.87 P < .0001). This pattern was not seen in men.

And patients with hypertension showed a borderline increased risk of SSNHL if they had osteoporosis compared with the controls (IRR, 1.59; P = .0465).

Dr Tien added that patients with more severe osteoporosis may have a higher risk of SSNHL than patients with less severe osteoporosis.

Using bisphosphonate therapy as a marker for disease severity, they found that the hazard ratio (HR) for SSNHL in osteoporotic patients who had received bisphosphonate therapy was 2.46, compared with the control group (P = .0005), compared withosteoporotic patients who had not received bisphosphonate therapy (HR, 1.64; P = .0003).

"Our study cannot answer if early detection and treatment of osteoporotic patients with antiosteoporotic therapy can reduce the risk of SSNHL," he said, noting that further prospective and intervention studies are needed to resolve this question.

Possible Mechanisms Driving Association

Previous studies suggest that osteoporosis might contribute to the development of SSNHL via the effects on the cardiovascular system.

"Since these two diseases [osteoporosis and SSNHL] might share similar risk factors — vascular inflammation and endothelial dysfunction — they have been reported to be associated with cardiovascular disease in epidemiological studies," explained Dr Tien.

But "after matching and adjustment for comorbid illness and risk factors, there remained a significant relationship between osteoporosis and SSNHL, implying that these comorbid illnesses and risk factors cannot explain the relationship entirely," he added.

Offering another possible mechanism, he said osteoporosis "is a kind of systemic demineralization and may not spare the temporal bone, which contains the cochlea capsule and the conductive system."

He and his colleagues refer to a previous study that reported an increased level of inflammatory cytokines such as interleukin (IL)-6, and tumor-necrosis-factor–alpha (TNF-α) in patients with osteoporosis. Such cytokines are also considered to play an important role in inflammatory bone destruction, and there is a close association between systemic inflammation and SSNHL, they write.

In conclusion, it is likely that "cardiovascular risk factors, bone demineralization, inflammation, and endothelial dysfunction should have roles linking osteoporosis and SSNHL," Dr Tien observed.

The authors report no relevant financial relationships.

J Clin Endocrinol Metab. Published online April 16, 2015. Abstract

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