Friday March 5 2010
Can taking painkillers increase risk of hearing loss?
“Common painkillers ‘increase the risk of hearing loss’”, reported The Daily Telegraph.
This story is based on research on whether frequent use of aspirin, ibuprofen, and paracetamol increase the risk of hearing loss in men. It found that men who took any of these drugs more than twice a week had a small increased risk of hearing loss. This type of study can only find associations, and it does not prove that the painkillers caused the hearing loss in these men. It also did not assess why the men were taking painkillers, and it is possible that the cause of their underlying pain may have had an effect on their hearing.
Hearing loss is already an established, potential side effect of these drugs, but only regular, high doses were thought to increase risk. This study indicates there may be increased risk, albeit a small one, with lower doses as well. Further work is needed to see if this is the case and to accurately quantify the dosage and duration of use that most poses a risk to hearing. In any case, anyone who is regularly taking painkillers for any unexplained long-term pain should consult with their GP.
Where did the story come from?
This research was carried out by Dr Sharon G Curhan and colleagues from Harvard University Brigham and Women’s Hospital and Harvard School of Public Health. The study was funded by the National Institutes of Health and Massachusetts Eye and Ear Infirmary Foundation. The paper was published in the peer-reviewed The American Journal of Medicine.
The research was clearly and accurately covered by the Telegraph. However, the paper did not emphasise that this study only showed an association between hearing loss and frequent painkiller use and did not demonstrate that frequent painkiller use causes hearing loss through a toxic effect.
What kind of research was this?
This cohort study investigated whether the use of painkillers is associated with hearing loss. The researchers suggest that painkillers have been shown to cause hearing loss when taken in high doses (several grams per day). As painkillers are widespread and regularly used by a large proportion of the population, the researchers wanted to see whether taking them frequently, even at a low dose, would be associated with hearing loss.
What did the research involve?
The researchers used data from a large cohort study (The Health Professionals Follow-up Study). This study began in 1986 and enrolled 51,529 male health professionals, aged 40 to 75 years, and followed them for a further 18 years. Every alternate year, the participants completed questionnaires on their diet, medical history and medication use. Painkillers questioned included aspirin, NSAIDs (such as ibuprofen) and acetaminophen (paracetamol). If the participants took these medications two or more times a week, this was defined as regular use. The 2004 questionnaire asked the men whether they had been diagnosed with hearing loss.
The researchers excluded anyone who had been diagnosed with hearing loss before 1986, or who had cancer and therefore may have been treated with drugs that could affect their hearing. As hearing loss is common with increasing age, they also excluded men as they reached the age of 75 in the follow-up. This left the researchers with data from 26,917 men.
In the analysis, the results were adjusted for other factors that may affect hearing. These included age, race, body mass index, alcohol intake, folate intake, physical activity, smoking, hypertension, diabetes, cardiovascular disease, elevated cholesterol and the use of furosemide (a type of diuretic).
What were the basic results?
Within the 20-year study period, 3,488 of the men were diagnosed with hearing loss. After adjustment for other factors that can affect hearing loss, men who regularly took painkillers had a higher risk of developing hearing loss than men who took them less than twice per week. Each type of painkiller was associated with a different increase in risk:
- 12% increase in the risk of developing hearing loss in men who took two or more aspirin a week (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.04 to 1.20);
- 21% risk increase in men taking two or more NSAIDs per week (HR 1.21, 95% CI 1.11 to 1.33);
- 22% risk increase in men taking two or more paracetamol per week (HR 1.22, 95% CI 1.07 to 1.39).
The researchers then looked at the length of time that the participants had regularly used painkillers and whether this had an effect on the risk of hearing loss. They compared the risk of hearing loss in participants that had taken painkillers regularly for four or more years, with those who were not regular users.
Long-term regular users of aspirin were 28% more likely to develop hearing loss than non-regular users. Regular NSAID users were 33% more at risk, the same result as for paracetamol users.
Age had an effect on risk, with a lower risk for men who were over 60 compared with younger men. For example, in the under 50 group the risk to hearing of regular aspirin use compared to non-regular use was 33% (hazard ratio); however, in the over 60s this relative risk was 3% (and was not significant). All three painkillers were associated with a lower risk in older men.
How did the researchers interpret the results?
The researchers conclude, “regular analgesic use was independently associated with an increased risk of hearing loss. The increased risk of hearing loss seen with regular analgesic use was greatest among younger men”.
They added, “given the high prevalence of regular analgesic use and health and social implications of hearing impairment, this represents an important public health issue”.
This study found an association between regular use of three types of painkiller and a small increased risk in hearing loss. This type of study can only find associations, it cannot demonstrate that these painkillers caused the hearing loss. The researchers highlight some limitations of their study:
- Men were categorised as having hearing loss based on their own admission in the questionnaire on whether it had been diagnosed by a professional. Participants who did not report hearing loss were considered to not be impaired. The best way to assess hearing would have been through standard pure-tone audiometry, but this could not be performed due to cost and logistics reasons.
- The researchers did not have information on the participants’ lifetime noise exposure or the reasons why they took painkillers. It may be the case that the underlying cause of the pain affected the men’s hearing. In addition, there may have been differences between the regular or non-regular users of painkillers in how likely it would be for them to consult a doctor for a hearing test.
- The research was carried out in a population of predominantly white, male health professionals, and it may not be appropriate to generalise the results outside of this population.
- The three types of painkillers assessed in this research work in different ways to ease pain. The researchers did not test potential mechanisms for the increased risk in this study.
This study found painkillers to be associated with a small increased hearing loss. Certain groups of medications are already known to be associated with hearing loss, and this includes aspirin and NSAIDs along with certain antibiotics, chemotherapy drugs and diuretic (‘water’) medications. However, aspirin and NSAIDs are only thought to increase risk with high daily doses taken on a regular basis. Painkillers should always be used within the recommended dose and only as required. Anyone using these painkillers for any unexplained long-term pain should consult their GP.