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Evid Based Nurs 10:88 doi:10.1136/ebn.10.3.88
  • Treatment

Daily folic acid supplementation for 3 years reduced age related hearing loss


 
 Q Is daily folic acid supplementation for 3 years more effective than placebo for reducing age related hearing loss in older adults?

METHODS

GraphicDesign:

substudy of a randomised, placebo controlled trial (Folic Acid and Carotid Intima media Thickness trial [FACIT]).

GraphicAllocation:

concealed.

GraphicBlinding:

blinded {patients, healthcare providers, data collectors, outcome assessors, data analysts, statisticians, data safety and monitoring committee, and manuscript writers}.*

GraphicFollow up period:

3 years.

GraphicSetting:

Gelderland province, the Netherlands.

GraphicParticipants:

819 participants 50–70 years of age (mean age 60 y, 72% men) with total plasma homocysteine concentrations of 13–26 μmol/l and serum vitamin B12 concentrations ⩾200 pmol/l were recruited using municipal and local blood bank registries. 48 participants had ⩾1 household member who was also enrolled and received the same treatment as the previously randomised member. Participants also had to report ⩾80% adherence during a 6 week placebo run in period. Exclusion criteria included hearing problems not likely caused by age related hearing loss (eg, middle ear dysfunction or unilateral hearing loss); self reported renal, thyroid, or intestinal disease or terminal cancer; or use of vitamin B supplements or medications that affect folate metabolism or atherosclerotic progression. 728 participants were included in the hearing substudy (91 participants were excluded because of middle ear or asymmetric hearing loss).

GraphicIntervention:

folic acid, 800 μg/d (n = 355), or matching placebo (n = 373).

GraphicOutcomes:

3 year change in average pure tone air conduction hearing thresholds (loudness of a just audible tone) of both ears at low (0.5, 1, and 2 kHz) and high (4, 6, and 8 kHz) frequencies assessed using audiometry.

GraphicPatient follow up:

all 728 participants were included in the intention to treat analysis; 16 participants who were lost to follow up were assigned the median hearing thresholds of the total study population at 3 years.

MAIN RESULTS

At baseline, median hearing threshold for low frequencies was 11.7 dB and for high frequencies was 34 dB. At 3 years, the folic acid group had less of an increase in low frequency hearing thresholds (ie, less hearing loss) than the placebo group (table). Groups did not differ for changes in high frequency hearing thresholds (table).

Folic acid v placebo for age related hearing loss

CONCLUSION

In older adults with symmetrical sensorineural hearing loss, daily folic acid supplementation for 3 years reduced the decline in hearing of low frequencies and had no effect on hearing of high frequencies.

Commentary

  1. Carolyn Auerhahn, APRN, EdD, BC, NP-C, FAANP
  1. New York University College of Nursing,
 New York, NY, USA

      Hearing loss is the third most common chronic condition in older adults, ranging from a prevalence of 25–40% in those 65–74 years of age to >80% in those >85 years.1 Age related sensorineural hearing loss, characterised by high frequency loss, accounts for approximately 90% of all hearing loss in older people. Loss is progressive, usually permanent, and available treatments are often ineffective. The associated psychosocial effects, such as depression, social isolation, and lack of confidence, greatly affect quality of life.

      Recent research suggests a link between homocysteine concentrations and hearing loss and provides the basis for the intervention in this study—folic acid supplementation.2,3 Durga et al address this important age related problem by focusing on slowing its progression. The generalisability of findings may be limited because treatment was only given to participants with very high homocysteine concentrations in a country that does not mandate adding folic acid to foods. Although there was no effect on high frequency hearing loss (possibly because of the long standing nature of the problem in the participants), it is possible that slowing the decline of hearing loss may result in delayed need for hearing aids.

      An important clinical implication of this study is its focus on risk factor reduction. Although sensorineural hearing loss is not associated with a high mortality rate, it can substantially affect physical and mental health and quality of life. As such, efforts focused on preventative interventions are warranted. In countries where folic acid is already added to foods, nurses may wish to wait for more research on the effects of further folic acid supplementation before changing advice and practice.

      References

      Footnotes

      • * Information provided by author.

      • For correspondence: Dr J Durga, Nestlé Research Center, Lausanne, Switzerland. jane.durga{at}rdls.nestle.com

      • Sources of funding: the Netherlands Organisation for Health Research and Development and Wageningen Centre for Food Sciences.

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