Published online June 1, 2007
PEDIATRICS Vol. 119 No. 6 June 2007, pp. e1408-e1412 (doi:10.1542/peds.2006-2881)

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EXPERIENCE & REASON

Incidence of Acute Otitis Media and Sinusitis Complicating Upper Respiratory Tract Infection: The Effect of Age

Krystal Revai, MD, MPH^a, Laura A. Dobbs, MD^b, Sangeeta Nair, DVM, MS^a, Janak A. Patel, MD^a, James J. Grady, DrPH^c and Tasnee Chonmaitree, MD^a,d

^a Department of Pediatrics
^b School of Medicine
^c Preventative Medicine & Community Health
^d Department of Pathology, University of Texas Medical Branch, Galveston, Texas

ABSTRACT

Infants and young children are prone to developing upper respiratory tract infections, which often result in bacterial complications such as acute otitis media and sinusitis. We evaluated 623 upper respiratory tract infection episodes in 112 children (6–35 months of age) to determine the proportion of upper respiratory tract infection episodes that result in acute otitis media or sinusitis. Of all upper respiratory tract infections, 30% were complicated by acute otitis media and 8% were complicated by sinusitis. The rate of acute otitis media after upper respiratory tract infection declined with increasing age, whereas the rate of sinusitis after upper respiratory tract infection peaked in the second year of life. Risk for acute otitis media may be reduced substantially by avoiding frequent exposure to respiratory viruses (eg, avoidance of day care attendance) in the first year of life.

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Key Words: otitis media • sinusitis • incidence • age

Abbreviations: AOM, acute otitis media • URI, upper respiratory tract infection • AAP, American Academy of Pediatrics • RR, rate ratio • CI, confidence interval • PCV7, heptavalent pneumococcal conjugate vaccine

Acute otitis media (AOM) and sinusitis are 2 of the most common bacterial complications of upper respiratory tract infections (URIs) in children. It has been found that 29% to 50%^1,2 of all URIs develop into AOM and 5% to 10% develop into sinusitis.³ Considering the exceedingly high incidence of URIs, the number of children affected by AOM and sinusitis comes as no surprise. On average, a child younger than 5 years of age has 2 to 7 episodes of URI per year,^4,5 and a child attending day care may have up to 14 episodes per year.⁶ By age 3, 80% of children have had at least 1 episode of AOM,⁷ and 13% have had sinusitis.⁸ The peak age of incidence of AOM is between 6 and 18 months, compared with 2 to 6 years for sinusitis.⁸ Despite the frequency of these infections and their close association with URIs, there has been no study to date that determines the age-specific incidence of AOM and sinusitis after a URI.

AOM and sinusitis are linked in several ways and may even occur concurrently. Both diseases are frequently preceded by a URI. Although AOM usually occurs between days 3 and 8 of a URI, sinusitis is not usually diagnosed until 10 to 14 days of persistent URI symptoms with no signs of improvement.⁹ The middle ear and sinuses have ciliated pseudostratified columnar cells that are similarly effected by viral URI. Finally, in children the 2 diseases are primarily caused by the same bacteria: Streptococcus pneumoniae, nontypeable Haemophilus influenzae, and Moraxella catarrhalis; thus, the type of antibiotic medication for treatment is similar.^3,10

This study is an analysis of the age incidence of AOM and sinusitis after URI in a subgroup of children who were enrolled in an ongoing long-term study of the pathogenesis of virus-induced AOM. We calculated the overall incidence of AOM and sinusitis after a URI episode as well as the age-specific incidence and determine if age played a role in the occurrence of AOM and sinusitis after URI.

METHODS

Healthy children aged 6 to 35 months were enrolled from January 2003 to March 2006 in a prospective, longitudinal study of virus-induced AOM (unpublished study). Children with chronic medical problems or with an anatomic or physiologic defect of the ear or nasopharynx were not enrolled. The study was designed to capture all URI episodes that occurred during the 1-year follow-up period to study the rate and characteristics of AOM after URI. At enrollment, demographic and AOM risk-factor information was collected. Parents were asked to call the study office as soon as the child began to have URI or AOM symptoms (cough, runny nose, fever, or ear pain or tugging). Children were seen by a study physician as soon as possible after the onset of URI symptoms and then followed again a few days later (days 3–7 of the URI) for URI complications. At each physician visit, parents were asked about current URI symptoms, current medications, and history of viral illness exposure. Tympanometry was performed, and the children were examined including pneumatic otoscopy. Each URI episode was studied and monitored closely for at least 3 weeks for the development of AOM or sinusitis. AOM complicating URI was considered when the episode occurred within 21 days of the URI. AOM and sinusitis diagnoses followed established guidelines published by the American Academy of Pediatrics (AAP)^9,11 and the Joint Task Force on Practice Parameters for Allergy and Immunology.⁸

AOM was defined by acute onset of symptoms (fever, irritability, or earache), signs of inflammation of the tympanic membrane, and presence of fluid in the middle ear documented by pneumatic otoscopy and/or tympanometry.¹¹ Sinusitis complicating URI was considered when children had persistent URI symptoms for >10 days without improvement or an abrupt increase in severity of symptoms, fever, or purulent nasal discharge before day 10 of illness.⁹ Children who were diagnosed with AOM or sinusitis were given antibiotic therapy consistent with the standard of care.

Parents were called twice monthly for information about current URI symptoms and the occurrence of any URI or AOM episodes since the last contact. Parents were reminded to call the study representative with any signs of URI or AOM. Any parent who could not be reached by telephone was sent a letter asking that they contact the study office. We performed an extensive chart review, including electronic medical charts, at each child's completion of the study. Because our institution is the sole provider of pediatric health care on Galveston Island, Texas, diseases that have been diagnosed and treated in our children are very likely to be within our medical charts.

All URI, AOM, and sinusitis episodes were included in the analysis. Data were analyzed by ² using Stata 9.0 (Stata Corp, College Station, TX). Rate ratios (RRs) were calculated by Episheet 2001, spreadsheets for the analysis of epidemiologic data.¹¹

RESULTS

This report consists of data from 112 patients who completed the study as of October 2005. Fifty five (49%) of the patients were male, 25 (22%) were white, 34 (30%) were black, 47 (42%) were Hispanic, and 6 (5%) were of other races. The mean and median ages of the children at enrollment were 15 and 13 months, respectively. Sixty-four percent of the children were fully immunized with heptavalent pneumococcal conjugate vaccine (PCV7) according to the Advisory Committee on Immunization Practices schedule. The mean and median number of weeks of breastfeeding was 16 and 23, respectively; 37% of the children were breastfed for >2 weeks. Thirty percent of the children were enrolled in day care (18% percent of the 6- to 11-month-olds, 40% of 12- to 23-month-olds, and 44% of 24- to 35-month-olds). Twenty-nine percent of the children were exposed to cigarette smoke.

The children were followed for a total of 1231 patient-months, during which time a total of 623 URI episodes occurred; the URI episodes resulted in 188 AOM and 52 sinusitis episodes. There were 17 episodes of AOM that did not follow a URI. The study-group physicians diagnosed 77% of the AOM and sinusitis episodes. All AOM episodes that were diagnosed by a study-group physician met the diagnostic criteria according to AAP guidelines. The other 23% of the AOM episodes were diagnosed by primary care or emergency department physicians. The overall incidence of URI was 0.51 per patient-month (6.12 episodes per patient-year), of AOM was 0.15 per patient-month (2.01 episodes per patient-year), and of sinusitis was 0.04 per patient-month (0.48 episodes per patient-year). Thirty percent of all URIs were complicated by AOM and 8% were complicated by sinusitis, including 15 URI episodes (2%) that were complicated by both AOM and sinusitis (47% concomitantly and 53% sequentially; most children were given a diagnosis of AOM before sinusitis). One child had an episode of AOM followed by persistent AOM and sinusitis, and 1 child had AOM and sinusitis diagnosed at the same time but developed persistent sinusitis. The majority of AOM episodes (81%) occurred in the first 8 days of illness (range: 1–19 days). The peak days of diagnosis were on days 3 and 5 (14% and 13%, respectively). Fifty-seven percent of AOM episodes were diagnosed in the first week of the URI. Fifteen (29%) of the sinusitis episodes were diagnosed because of an abrupt increase in severity of symptoms, fever, or purulent nasal discharge before day 10 of illness; the remainder were diagnosed on the basis of persistence of symptoms beyond 10 days.

Children in the 6- to 11-month-old and 12- to 23-month-old age groups had the same incidence of URI (0.51 episodes per patient-month). Children in the third year of life had 0.48 URI episodes per patient-month. Children who attended day care had a URI rate of 0.59 URI episodes per patient-month, compared with 0.47 URI episodes per patient-month in children who did not attend day care (RR: 1.2; 95% confidence interval [CI]: 1.1–1.4; P = .01). AOM occurred after URI in 36% of episodes in children 6 to 11 months old (Fig 1), 29% of episodes in children in the second year of life, and 15% of episodes in children in the third year of life (P < .001 by Fisher's exact test). Older children tended to have fewer AOM episodes after URI (P < .001 by the Cochrane-Armitage trend test). Sinusitis complicated URI in 7%, 10%, and 7% of episodes in children from 6 to 11, 12 to 23, and 24 to 35 months, respectively. The rate of AOM after URI was 30% in PCV7-immunized children and 27% in PCV7-unimmunized children (RR: 1.09; 95% CI: 0.88–1.39). The rates for sinusitis were 7% and 9% of episodes in immunized and unimmunized children, respectively (RR: 0.9; 95% CI: 0.63–1.26).

View larger version (16K): [in this window] [in a new window]   FIGURE 1 AOM and sinusitis incidence according to age. AOM occurred more often after URI in younger children (P < .001 by Fisher's exact test). AOM incidence decreased with increasing age (Cochrane-Armitage trend test). N indicates number of URI episodes.

 

DISCUSSION

It is well established that the peak age for AOM is between 6 and 18 months.^7,13,14 More recent data have suggested that AOM generally occurs as a complication of viral URI.¹⁵ In this study, we clearly demonstrate that 30% of URI episodes in children result in AOM, and the disease occurs most often in children between 6 and 11 months of age, although these children are as susceptible to URI as children in the second year of life. We also found that sinusitis after URI occurs less frequently than AOM (8%), and the disease was more commonly diagnosed in children from 12 to 23 months of age.

For otitis media to occur, bacteria colonized in the nasopharynx must enter the middle ear via the eustachian tube. Normally, bacteria are prevented from entering the middle ear by the ciliated epithelium that lines the eustachian tube. Respiratory virus infection disrupts the mucociliary system and impairs the ear's primary mechanical defense from bacterial invasion. In addition, eustachian-tube dysfunction can lead to reduced middle-ear pressure, which forces mucus, nasopharyngeal secretions, and bacteria into the middle ear; this creates an ideal milieu for bacterial superinfection.¹⁶

We found the highest incidence of AOM after URI to be between 6 and 11 months of age, and these data parallel what was found by Teele et al.⁷ The increased susceptibility to AOM in younger children has been postulated to be secondary to inadequate immunologic response and a shorter, straighter, and narrower Eustachian tube.¹⁰ It stands to reason that the longer children are protected from exposure to known avoidable otitis media risk factors, the later the onset of AOM and the lower their lifetime incidence.

Children who are cared for in a day care setting are exposed to many more infectious diseases, including viral URI, than children who do not attend day care.⁶ In our study, as in other studies,¹⁷ we show that children who attend day care have a higher burden of disease with regard to respiratory illness. Our study likely did not show a strong correlation because it was not designed to examine day care attendance. It has also been found that the later the children start group day care, the later the onset of otitis media with effusion (OME). There is a positive association between the amount of time spent in group child care and the amount of AOM and OME episodes.^18,19 In our study, although children in their second and third years of life were more likely to attend day care, and thus more frequently exposed to viral pathogens than young infants, they were less likely to develop AOM. These data suggest that keeping the most vulnerable age group of children (eg, <1 year of age) out of the day care setting and protecting them from exposure to respiratory infections may substantially reduce AOM incidence. In children who are prone to development of AOM, parents should be advised of these risk factors, as well as other well-established risk factors such as lack of breastfeeding and cigarette-smoke exposure.¹⁹

The pathophysiologic processes that occur in paranasal sinuses during a viral URI are similar to those that occur in the middle ear. The ciliated epithelium in the sinuses also loses its ability to move debris from the nasal cavity. When a child sniffs or blows his or her nose, negative pressure is formed within the sinus cavity, which draws in bacteria and debris, once again creating a model environment for bacteria to proliferate and cause sinusitis. Nevertheless, sinusitis is still a disease with a much lower incidence than AOM.

The diagnosis of sinusitis, in general, holds some degree of uncertainty, especially in children under 1 year old. Although the AAP clinical practice guidelines provide recommendations for diagnosis and treatment of sinusitis in children over 1 year old,⁹ sinusitis is sometimes diagnosed in children who are under 12 months old. In our study, there were 18 (35%) episodes of sinusitis diagnosed in infants under 12 months of age.

The majority (83%) of the sinusitis episodes in our patients were diagnosed by a study physician following the published diagnostic criteria.⁹ We found that the incidence of sinusitis was lower in the 6- to 11-month age group and in children over 24 months old when compared with children who were 12 to 23 months old, but the difference did not reach statistical significance. We postulate that the incidence of sinusitis may peak in the 12- to 23-month-old children because they are less likely to develop AOM and, thus, less likely to have received antibiotic therapy. Therefore, any low-grade bacterial infection in the sinuses would go unnoticed until cleared by the child's own natural defense or progress to clinical sinusitis, requiring subsequent initiation of antibiotic therapy. Children in their third year of life may possibly have a lower incidence of AOM and sinusitis because they have already developed partial immunity to many microbial pathogens and subsequently do not have a strong inflammatory response to infection. This study was not powered to determine a difference in the incidence of sinusitis. Another study targeted at sinusitis may clarify these differences further.

In our study, it is possible that a number of URIs were not reported to us even though we were in very frequent contact with the parents. Nevertheless, the overall incidence of URI and AOM is within the ranges of those reported previously.^1,2,4,5 Although the majority of URI episodes were seen by the study group, we captured another 23% of the total number of URI episodes either by parent-initiated contact, twice-monthly parental telephone calls, or chart review. Mild URI, especially in older children, may have gone unnoticed and unattended by parents; therefore, unreported URI episodes were likely to occur more often in older children than in younger ones. It is also possible that parents failed to seek medical attention for the child's URI, or more often than for AOM or sinusitis. If missed URI episodes occurred more often than missed AOM or sinusitis episodes, then the actual incidence of AOM and sinusitis after URI could be somewhat lower than reported. Incidence according to age group should still be proportionate or even lower than reported in older age groups, which would widen the difference between the 3 groups. URI, AOM, and sinusitis diagnosed by physicians other than those in the study group were unlikely to be missed.

CONCLUSIONS

We found that children from 6 to 11 months of age were at highest risk for developing AOM after URI. Older children were more likely to attend day care yet developed fewer episodes of AOM and sinusitis. Delaying entry into group day care until the second year of life could help reduce the incidence of AOM in infants and young children.

ACKNOWLEDGMENTS

This work was supported by National Institutes of Health grants R01 DC005841 and DC 005841-02S1. The study was conducted at the General Clinical Research Center at the University of Texas Medical Branch, which is funded by National Center for Research Resources (National Institutes of Health, US Public Health Service) grant M01 RR 00073.

We thank M. Lizette Rangel, Kyralessa B. Ramirez, Liliana Najera, and Rafael Serna for assistance with study subjects.

FOOTNOTES

Accepted Nov 28, 2006.

Address correspondence to Tasnee Chonmaitree, MD, Department of Pediatrics, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-0371. E-mail: tchonmai{at}utmb.edu

The authors have indicated they have no financial relationships relevant to this article to disclose.

This work was presented in part at the annual meeting of the Pediatric Academic Societies; April 29–May 2, 2006; San Francisco, CA.

Dr Dobbs' current affiliation is Department of Pediatrics, Eastern Virginia Medical School, Norfolk, VA.

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PEDIATRICS (ISSN 1098-4275). ©2007 by the American Academy of Pediatrics

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