Association of Long-Term Risk of Respiratory, Allergic, and Infectious Diseases With Removal of Adenoids and Tonsils in Childhood

Abstract

Importance: Surgical removal of adenoids and tonsils to treat obstructed breathing or recurrent middle-ear infections remain common pediatric procedures; however, little is known about their long-term health consequences despite the fact that these lymphatic organs play important roles in the development and function of the immune system.

Objective: To estimate long-term disease risks associated with adenoidectomy, tonsillectomy, and adenotonsillectomy in childhood.

Design, setting, and participants: A population-based cohort study of up to 1 189 061 children born in Denmark between 1979 and 1999 and evaluated in linked national registers up to 2009, covering at least the first 10 and up to 30 years of their life, was carried out. Participants in the case and control groups were selected such that their health did not differ significantly prior to surgery.

Exposures: Participants were classified as exposed if adenoids or tonsils were removed within the first 9 years of life.

Main outcomes and measures: The incidence of disease (defined by International Classification of Diseases, Eighth Revision [ICD-8] and Tenth Revision [ICD-10] diagnoses) up to age 30 years was examined using stratified Cox proportional hazard regressions that adjusted for 18 covariates, including parental disease history, pregnancy complications, birth weight, Apgar score, sex, socioeconomic markers, and region of Denmark born.

Results: A total of up to 1 189 061 children were included in this study (48% female); 17 460 underwent adenoidectomy, 11 830 tonsillectomy, and 31 377 adenotonsillectomy; 1 157 684 were in the control group. Adenoidectomy and tonsillectomy were associated with a 2- to 3-fold increase in diseases of the upper respiratory tract (relative risk [RR], 1.99; 95% CI, 1.51-2.63 and RR, 2.72; 95% CI, 1.54-4.80; respectively). Smaller increases in risks for infectious and allergic diseases were also found: adenotonsillectomy was associated with a 17% increased risk of infectious diseases (RR, 1.17; 95% CI, 1.10-1.25) corresponding to an absolute risk increase of 2.14% because these diseases are relatively common (12%) in the population. In contrast, the long-term risks for conditions that these surgeries aim to treat often did not differ significantly and were sometimes lower or higher.

Conclusions and relevance: In this study of almost 1.2 million children, of whom 17 460 had adenoidectomy, 11 830 tonsillectomy, and 31 377 adenotonsillectomy, surgeries were associated with increased long-term risks of respiratory, infectious, and allergic diseases. Although rigorous controls for confounding were used where such data were available, it is possible these effects could not be fully accounted for. Our results suggest it is important to consider long-term risks when making decisions to perform tonsillectomy or adenoidectomy.

Figure 1.. Age at Adenoidectomy, Tosillectomy, and Adenotonsillectomy for 1 753 100 Danes Born Between 1979 to 2009 and the Selected Surgery Observation Window of 9 Years

This cut-off for inclusion as surgery cases (dark blue bars) was deemed optimal because the first decade of life is critical for normal immune system development, it represents most of the period in which these surgeries are usually performed, and maximized the number of years available for disease follow-up after surgery. For tonsillectomy this meant that we ignored a second peak at approximately 16 to 17 years because inclusion of these surgeries would have implied insufficient time for follow-up (to 30 years). Our study thus explores the impact of the 3 types of surgery when performed during childhood rather than adolescence. Individuals with these surgeries beyond the 9-year observation end point (dotted vertical line) were not included as either cases or controls. Individuals were also excluded if they had multiple surgeries at different ages, ie, some individuals underwent adenoidectomy followed by tonsillectomy years later or vice versa. Such cases were rare in the sample (<0.2%).

Figure 2.. Risk of Disease up to Age 30 Years After Removal of Tonsils and Adenoids in the First 9 Years of Life

Abbreviation: COPD, chronic obstructive pulmonary disorder. Relative risks (RR) and 95% CIs are the exponents from Cox regressions that capture risk of each disease up to age 30 years depending on whether surgery was performed. The RR P values significant after Bonferroni corrections for 78 tests are shown by a blue point above the upper confidence interval for each disease. The RR values are presented only for analyses with sufficient power for hypothesis testing (see methods). Absolute risk differences (ARD) and 95% CIs were estimated as ARD = 100 × CR × (1-RR), where CR (control risk) is the risk of the disease in the control sample and RR is the relative risk of disease in individuals post-surgery relative to the disease risk in the control sample that did not undergo surgery. Numbers needed to treat (NNT) and 95% CIs were estimated as NNT = 100/ARD. The NNT values above or below zero indicate harm or benefit associated with surgery, respectively, with values closer to 0 indicating harm occurring more often to patients. For example, for risk of asthma after adenoidectomy (ie, RR = 1.45; 95% CI, 1.33-1.57), the event rate in the control group (or control risk, CR) for asthma up to age 30 years in our dataset was 5.8%, ARD = |100 × 0.058 x (1−1.45)| = 2.6 and NNT = 100/2.6 = 38. Relative risk of asthma was 1.45 and thus 45% higher after adenoidectomy compared with controls (no surgery), which translates to an absolute risk difference of 2.6% or 2.6 more cases of asthma per 100 treated patients. In other words, approximately 38 adenoidectomies would need to be performed for an additional asthma diagnosis to be associated with one of those patients in the first 30 years of life. Note: urinary tract infections were not included in the kidney infection group.

Figure 3.. Disease Risk Patterns for Covariates

Relative risk magnitude and direction correspond to red (increased relative risk) and purple (decreased relative risk) colors derived from Cox regressions capturing the risk of diseases (vertical axis) within the first 30 years of life depending on 21 covariates (horizontal axis). Within each circle there are 3 divisions corresponding to surgery type. A black border indicates whether risk for that particular disease-covariate combination was significant after Bonferroni correction for 78 tests; a complete black border surrounding a circle indicates that risks were significant for all 3 surgeries. Disease risks for the covariate region most lived in Denmark are relative to Hovedstaden (Copenhagen region). Note: Urinary tract infections were not included in the kidney infection group.