Phosphodiesterase Type 5 Inhibitor Use and Hearing Impairment Objective: To compare use of phosphodiesterase type Results: The overall prevalence of self-reported hearing
5 inhibitors (PDE-5i) between participants with and with-
impairment and PDE-5i use in each group was 17.9% and
out self-reported hearing impairment using logistic
2%, respectively. Men who reported hearing impairment
regression, with and without adjustment for potentially
were more likely to have also reported the use of any PDE-5i
confounding sociodemographic, behavioral, and health-
(odds ratio [OR], 2.23; 95% confidence interval [CI], 1.36-
3.66). However, this association was limited to sildenafil(Viagra) (OR, 2.05; 95% CI, 1.23-3.43); no significant as-
Design: Cross-sectional.
sociations were observed for tadalafil (Cialis) or vard-enafil (Levitra) (ORs, 1.40 [95% CI, 0.49-4.04] and 0.88
Setting: United States. Patients: A population-based sample of 11 525 men 40 Conclusions: Current warnings regarding the risk of
years or older (248 217 013 weighted men) in the United
hearing loss related to PDE-5i use seems to be justified.
States, selected from the Medical Expenditure Panel Sur-
However, the cross-sectional nature of the current study
provides only limited insight regarding this relation-ship, and thus additional research is warranted. Main Outcome Measure: Self-reported hearing impairment. Arch Otolaryngol Head Neck Surg. 2010;136(5):488-492HEARINGLOSS(HL)ISTHE PDE-5iuse.5ThispromptedtheFDAto
require that material associated with these
products mention the possibility of HL. De-
tails regarding most of the cases reported
tors contributing to its etiology. It is esti-
were subsequently described in the litera-
ence some type of hearing impairment.1 Risk
factors include age, sex, occupation, edu-
port to the notion that PDE-5i use may in-
cation, smoking, diabetes mellitus, and car-
diovascular disease.1-3 Genetic risk factors
tiple possible susceptibility genes have been
help fill this void in the current litera-
ture, this study evaluates this relation-
inhibitors (PDE-5i), including sildenafil ci-trate (Viagra and Revatio; Pfizer Inc, New
York, New York), vardenafil (Levitra; BayerHealthcare Pharmaceuticals, Montville,New Jersey, Schering-Plough, Kenil-
DATA SOURCE AND STUDY DESIGN
worth, New Jersey, and GlaxoSmithKline,London, England), and tadalafil (Cialis; Eli
The Medical Expenditure Panel Survey (MEPS)is a longitudinal, overlapping panel cohort, with
Lilly, Indianapolis, Indiana).5 Following
each cohort consisting of approximately 15 000
the published report of a single patient who
households, including a subsample of approxi-
experienced SSHL after taking sildenafil for
Author Affiliation: Department
mately 39 000 individuals chosen from the Na-
tional Health Interview Survey using a strati-
istration (FDA) identified a total of 29 re-
fied and clustered sample with weights that
ports of sudden HL potentially related to
produce nationally representative estimates.9
(REPRINTED) ARCH OTOLARYNGOL HEAD NECK SURG/ VOL 136 (NO. 5), MAY 2010
2010 American Medical Association. All rights reserved.
Participants are interviewed 5 times over a 2-year period with
cific condition. Medical conditions reported by respondents are
respect to demographic, health status, and health care utiliza-
coded by professional coders to International Classification of
tion, including prescription medication use. For the purposes
Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes,
of this cross-sectional study, data for men 40 years or older from
although, to protect respondent confidentiality, nearly all codes
the 2003-2006 MEPS Household Component (HC) were com-
are available only at the 3-digit level. This information was used
bined. These years have a common variance structure neces-
to identify the presence of diabetes mellitus and cardiovascu-
sary to ensure compatibility and comparability among the
lar disease, the latter including coronary heart disease, angina,
specific variables and represent the most recent data available.
myocardial infarction, or other heart conditions. Finally, the
The institutional review board at the University of Alabama at
MEPS collects information related to current and former jobs,
including industry and occupation. Industry and occupationcodes are assigned by professional coders at the US Census Bu-
VARIABLE DEFINITIONS
reau based on verbatim descriptions provided by respondentsduring the survey interview. The detailed codes are collapsed
Hearing Impairment
into broader groups to ensure confidentiality. For the pur-poses of this analysis, individuals were classified as having everworked in any of the following occupational categories: man-
The MEPS-HC respondents are asked a series of questions re-
agement/business/financial, professional, service, sales, office/
garding HL; these questions are asked of all household mem-
administrative, farming/fishing/forestry, construction, produc-
bers. Specifically, respondents are asked about the use of a hear-
ing aid, any difficulty hearing (with or without the use of ahearing aid), deafness, and the ability to hear most or some ofthings people say. Responses to these questions are summa-
STATISTICAL ANALYSIS
rized into a single variable that classifies individuals with re-spect to the extent of their hearing impairment. For the pur-
Given the complexity of the MEPS study design, it is neces-
poses of this study, individuals classified as having no hearing
sary to account for the sampling strategy as well as the longi-
difficulty are compared with those with slight, moderate, or ma-
tudinal nature of the data collection. To aid in the analysis of
jor HL or deafness. This same classification has been used pre-
data across several years, the MEPS provides weight and vari-
viously to describe the prevalence of HL in the United States.10
ance estimation variables that must be applied when produc-ing national estimates and appropriate estimates of variability
PDE-5i Use
for longitudinal analyses. Thus, all analyses conducted as partof this study use these statistical weights.
During each round of the MEPS-HC, all respondents are asked
Demographic, environmental, and medical characteristics
to supply the name of any prescribed medications they or their
were compared between those with and without hearing im-
family members purchased or otherwise obtained. For each
pairment using t test and 2 test for continuous and categori-
medication, a variety of information is obtained, including the
cal variables, respectively. The association between HL and
name(s) of any health problems for which the medicine was
PDE-5i use was estimated using logistic regression with and
prescribed, frequency of purchase, and the date of first use. For
without adjustment for the characteristics given in the “Poten-
the purposes of this study, respondents with reported use of
tial Confounders” subsection of the “Methods” section. P val-
sildenafil, vardenafil, and tadalafil were classified as PDE-5i us-
ues of Յ.05 (2-sided) were considered statistically significant.
ers; nonusers were those with no record of having reported useof these medications. Revatio is another PDE-5i used in the treat-ment of pulmonary arterial hypertension; however, no respon-
dent reported using it during the study period.
This analysis represents data on a total of 248 217 013
Potential Confounders
(11 525 unweighted) men 40 years or older in the UnitedStates from 2003 through 2006, approximately 62 mil-
A number of demographic, environmental, and medical char-
lion participants per year. These figures are comparable
acteristics have been linked to HL4 and therefore serve as po-
with US Census Bureau estimates for the male popula-
tential confounders for the relationship between PDE-5i use
tion 40 years or older during this same time period. The
and hearing impairment. Thus, in addition to sociodemo-
overall prevalence of HL was 17.9% and increased with
graphic characteristics (ie, age, race, household income), in-
age. The prevalence among those in their forties was 7.5%,
formation pertaining to current smoking, the use of ototoxicmedications, diabetes mellitus, cardiovascular disease, and job
and this increased to 15.0%, 24.4%, 32.9%, and 47.2%
characteristics was selected from the MEPS-HC. Information
in subsequent decades. Approximately 2% of men re-
regarding other potential confounders (eg, alcohol consump-
ported having obtained a PDE-5i; use was lowest among
tion) is not available in the MEPS, and therefore the confound-
those in their forties (0.8%), steadily increased until men
ing influence of such characteristics cannot be evaluated. Oto-
were in their 60s (3.3%), and then subsequently de-
toxic medication use, including antibiotics, diuretics, salicylates,
clined to 0.5% for men 80 years or older. Among those
and quinine derivatives, was defined using the same informa-
reporting PDE-5i use, sildenafil was the most frequently
tion source used to define PDE-5i use. Information on acute
used (80.3%), followed by vardenafil (20.2%) and tad-
and chronic medical conditions in the MEPS-HC is obtained
via a number of mechanisms, including the report of a medi-
Table 1 presents demographic and health-related
cal event (eg, hospital stay, medication purchase), whether thecondition was responsible for 1 or more disability days, or if
characteristics according to HL status. Those classified
the condition was reported as “bothering” the person. For cer-
as hearing impaired were approximately 10 years older,
tain conditions (eg, diabetes mellitus, coronary heart disease)
more likely to be white, and had lower household in-
respondents are asked explicitly whether they were told by a
comes compared with those not classified as such. Those
physician or other health care provider that they have a spe-
with hearing impairment were less likely to have worked
(REPRINTED) ARCH OTOLARYNGOL HEAD NECK SURG/ VOL 136 (NO. 5), MAY 2010
2010 American Medical Association. All rights reserved. Table 1. Sociodemographic, Health, and Behavioral Characteristics According to Self-Reported Hearing Impairmenta Hearing Impairment Characteristic (n = 9 125 761) (n = 239 091 252) P Value
a Data are given as percentages except where noted.
b Income based on family income relative to the poverty line (based on family size and composition). Table 2. Prevalence of Hearing Impairment According to Phosphodiesterase Type 5 Inhibitor (PDE-5i) Use and Associated Odds Ratios (ORs) and 95% Confidence Intervals (CIs) Hearing Impairment, % Unadjusted OR Adjusted OR PDE-5i Usea (n = 9 125 761) (n = 239 091 252) (95% CI)b
a Manufacturers’ information: Viagra, Pfizer Inc, New York, New York; Cialis, Eli Lilly, Indianapolis, Indiana; and Levitra, Bayer Healthcare Pharmaceuticals,
Montville, New Jersey, Schering-Plough, Kenilworth, New Jersey, and GlaxoSmithKline, London, England.
b Adjusted for age, race, household income, smoking, diabetes mellitus, cardiovascular disease, use of ototoxic medications, and occupation.
in the management or business field but more likely to
of PDE-5i use compared with those without HL. This as-
have worked in the construction industry or have been
sociation seemed to be limited to sildenafil use (odds ra-
in the military. There was no difference with respect to
tio [OR], 2.05; 95% confidence interval [CI], 1.23-
current smoking; however, individuals with hearing im-
3.43); there was no significant association for tadalafil
pairment were more likely to have diabetes mellitus, car-
(OR, 1.40; 95% CI, 0.49-4.04) or vardenafil (OR, 0.88;
diovascular disease, or used ototoxic medications com-
pared with those without such impairment. Table 2 presents the overall and medication-
specific prevalence of PDE-5i use among those with and
without HL. The use of any PDE-5i was more commonamong those with hearing impairment compared with
In 2007, the FDA announced labeling changes for PDE-5i
those without (3.0% vs 1.4%); a similar pattern was ob-
medications, including sildenafil, vardenafil, and tadala-
served for those taking specific PDE-5i medications, al-
fil,5 such that the risk of sudden hearing problems is more
though the differences were most apparent for those tak-
prominently displayed.5 To my knowledge, prior to the
ing sildenafil and tadalafil. The adjusted results indicate
current study, no epidemiologic studies had evaluated
that those with HL had more than 2-fold increased odds
this relationship. The current findings suggest that men
(REPRINTED) ARCH OTOLARYNGOL HEAD NECK SURG/ VOL 136 (NO. 5), MAY 2010
2010 American Medical Association. All rights reserved.
40 years or older with self-reported hearing impairment
a case report or series that lacks a suitable comparison
were more than twice as likely to report PDE-5i use com-
group, this is a reasonable concern. Another concern is
pared with those not reporting HL. This association per-
the fact most cases reported in the literature have been
sisted following adjustment for a number of potential
of patients found to have unilateral HL. Yet HL attribut-
demographic- and health-related confounding charac-
able to the toxic effects of PDE-5i use would be ex-
teristics. Moreover, this relationship seems to be lim-
pected to be bilateral. Finally, for several of the reported
ited to sildenafil use, although an elevated, yet not sta-
cases there is not a clear temporal relationship between
tistically significant, association was also observed for
the SSHL and PDE-5i use. Yet, for most (approximately
tadalafil. The lower frequency of tadalafil and vardenafil
90%) of the cases reported by Maddox et al,7 HL oc-
use may have precluded the identification of similarly in-
curred within 24 hours of taking a PDE-5i, and of those,
creased risks owing to limited statistical power. The as-
most cases occurred within 12 hours. Finally, the lack
sociation between PDE-5i use, specifically sildenafil, and
of information on potentially confounding characteris-
sensory impairment is not novel. In 2005, following a
tics has precluded definitive conclusions regarding
small case series, the FDA required that PDE-5i users be
warned about the risk of sudden-onset blindness or non-
The present study compared individuals with self-
arteritic ischemic optic neuropathy (NAION).11 A sub-
reported hearing impairment with those without such im-
sequent case-control study12 reported no significant as-
pairment and adjusted for the potentially confounding
sociation between NAION and sildenafil and/or tadalafil
influence of demographic- and health-related character-
use, although an increased risk was observed for those
istics. Thus, the concern that previously reported cases
with a family history of myocardial infarction. A reanaly-
may simply reflect the background incidence of hearing
sis of the data from this study revealed that any in-
impairment or confounding is diminished, although in-
creased risk was limited to sildenafil use (G.M., unpub-
formation on certain potential confounders was not avail-
able. My results suggest that the previously reported cases
Given the dearth of published literature regarding
may be over and above the natural incidence and possi-
PDE-5i medications and HL, it is difficult to place the
bly attributed to PDE-5i use. However, a number of the
results of the current study into context. One important
concerns mentioned herein could not be resolved in the
consideration in evaluating the nature of this relation-
current study. First, the study design was cross-
ship is the existence of a plausible biological mecha-
sectional, and thus I cannot evaluate the temporal rela-
nism. It has been hypothesized that PDE-5i might cause
tionship between the onset of HL in relation to timing,
HL owing to their ability to affect nasal physiologic char-
frequency, or duration of PDE-5i use; this is despite the
acteristics and thus eustachian tube function. Specifi-
longitudinal nature of MEPS. The structure of the ques-
cally, PDE-5i use causes congestion of nasal erectile tis-
tions regarding HL does not easily lend itself to the iden-
sue that results in elevated middle ear pressure.13,14 It has
tification of incident hearing problems. Second, I did not
also been suggested that PDE-5i may intensify the ef-
have information on SSHL but instead focused on self-
fects of nitric oxide, which has been implicated in a num-
reported hearing impairment. Although those with SSHL
ber of otologic diseases, or simulate the effects via acti-
are likely to be captured with questions about hearing
vated intracellular cyclic guanosine monophosphate
impairment in general, it is more than likely that they
(cGMP).7,8 The PDE-5i function by blocking the degra-
represent the minority of those with self-reported HL.
dation of cGMP, the accumulation of which induces gene
Given the observed results, if the association between
expression via transcription factors by protein phos-
PDE-5i use and SSHL is real, then it is either strong enough
phorylation by specific kinases, which themselves have
to overcome any misclassification or, and perhaps more
been associated with damage to cochlear hair cells.7 To
plausibly, PDE-5i use is associated with hearing impair-
my knowledge, no study has provided evidence for or
ment in general as well as SSHL specifically. That said,
against these mechanisms. However, nitric oxide is in-
there has been great debate regarding the usefulness of
creased following auditory organ injury, and high nitric
information regarding self-reported hearing impair-
oxide levels are associated with inner ear dysfunction15;
ment. It has been suggested that the sensitivity of self-
increased nitric oxide production has also been ob-
reported HL is low (ie, 41%-65%) compared with audio-
served in animals with HL.16-18 In addition, high doses
metric measurement,1 and that self-reported prevalence
of sildenafil have been observed to induce hearing im-
estimates may vary owing to the nature of the question
pairment in mice.8 In a study13 of 18 men using PDE-5i
being asked.10 However, others have been more optimis-
for erectile dysfunction, 4 showed a temporary decrease
tic regarding the usefulness of self-reported hearing
in hearing threshold, although no permanent deleteri-
impairment for documenting prevalence and trends20,21
ous effect was observed. Interestingly, it has been sug-
although greater caution is warranted when using self-
gested that vardenafil might be useful in the treatment
report for etiologic associations.21 Ultimately, in the con-
of tinnitus, although research has failed to support this
text of the present study the main concern is bias, and
there is no reason to expect PDE-5i users to differen-
Maddox et al7 expressed several concerns that argue
tially report HL; particularly because at the time the data
against a causal relationship between PDE-5i use and HL.
used in this study were collected, information regarding
These authors suggest that the published case reports of
the potential relationship between PDE-5i use and HL
SSHL attributed to PDE-5i may simply reflect the natu-
was not widespread. Moreover, risk factors for HL dem-
ral incidence of this condition rather than excess risk
onstrate a high degree of consistency whether impair-
posed by the use of these medications. In the context of
ment is defined via self-report or audiometry22,23 and have
(REPRINTED) ARCH OTOLARYNGOL HEAD NECK SURG/ VOL 136 (NO. 5), MAY 2010
2010 American Medical Association. All rights reserved.
been shown to have equivalent reductions in quality of
impairment: contributing environmental and genetic factors. Audiol Neurootol.
life.24 Thus, whether defined based on audiometry or self-
5. FDA announces revisions to labels for Cialis, Levitra and Viagra: potential risk of
report, the etiology of HL is likely to be similar.
sudden hearing loss with ED drugs to be displayed more prominently. US Food
Based on several case reports, the FDA required the
and Drug Administration Web site. http://www.fda.gov/NewsEvents/Newsroom
manufacturers of PDE-5i medications to warn users re-
/PressAnnouncements/2007/ucm109012.htm. Accessed July 21, 2009.
garding the potential for sudden-onset HL. While case
6. Mukherjee B, Shivakumar T. A case of sensorineural deafness following inges-
reports and the hypotheses they generate are often use-
tion of sildenafil. J Laryngol Otol. 2007;121(4):395-397.
7. Maddox PT, Saunders J, Chandrasekhar SS. Sudden hearing loss from PDE-5
ful in laying the foundation for future epidemiologic stud-
inhibitors: a possible cellular stress etiology. Laryngoscope. 2009;119(8):1586-
ies, they provide limited evidence for causality. The re-
sults of the current study in conjunction with a plausible
8. Hong BN, Yi TH, Kim SY, Kang TH. High dosage sildenafil induces hearing im-
biologic mechanism lend support to the FDA’s decision
pairment in mice. Biol Pharm Bull. 2008;31(10):1981-1984.
to warn patients about the potential risk posed by PDE-5i
9. Cohen SB. Design strategies and innovations in the medical expenditure panel
survey. Med Care. 2003;41(7)(suppl):III5-III12.
use. However, this support must be tempered in light of
10. Ikeda N, Murray CLJ, Salomon JA. Tracking population health based self-
the limitations mentioned herein. The largely irrevers-
reported impairments: trends in the prevalence of hearing loss in US adults,
ible nature of HL and its impact on quality of life under-
1976-2006. Am J Epidemiol. 2009;170(1):80-87.
score the need for additional research regarding the etio-
11. FDA updates labeling for Viagra, Cialis and Levitra for rare post-marketing re-
ports of eye problems. US Food and Drug Administration Web site. http://www
logic role of PDE-5i use. In the interim, it is prudent that
.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2005/ucm108458
patients using these medications, specifically sildenafil,
be warned about the signs and symptoms of hearing im-
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15. Watanabe K, Hess A, Zumeger C, et al. Changes of the compound action potential
Correspondence: Gerald McGwin Jr, MS, PhD, Depart-
(CAP) and the expression of inducible nitric oxide synthase (iNOS/NOS II) in thecochlea under the inflammatory condition. Hear Res. 2000;145(1-2):149-155.
ment of Epidemiology, University of Alabama at Bir-
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mingham, 1922 Seventh Ave S, Ste 120, Birmingham, AL
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legal counsel as an expert witness in cases related to silde-
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(REPRINTED) ARCH OTOLARYNGOL HEAD NECK SURG/ VOL 136 (NO. 5), MAY 2010
2010 American Medical Association. All rights reserved.
CURRICULUM VITAE NAME: Andrew O. Westfall, M.S. PREPARED : December 15, 2010 HOME ADDRESS / PHONE NUMBER: BUSINESS ADDRESS / PHONE NUMBER: BIRTHDATE: July xx, 1969 BIRTHPLACE: Charleston, West Virginia SOCIAL SECURITY NUMBER: MARITAL STATUS: EDUCATION: University of Florida Gainesville, Florida University of Florida MEMBERSHIPS IN PROFESSI
Concentración natural de compuestos antimaláricos en artrópodos tropicales ( in vitro ) Misael Chinchilla-Carmona1,3, Olga Marta Guerrero Bermúdez1, Giselle Tamayo-Castillo2,4, Ana Sittenfeld Appel2,5, Alberto Jiménez-Somarribas2 & Idalia Valerio-Campos31 Centro de Investigación en Enfermedades Tropicales, Departamento de Parasitología, Facultad de Microbiología, Universidad