Chronic Tonsillitis Associated with Increased Risk of IgA Nephropathy

Chronic tonsillitis may be associated with an increased risk of developing IgA nephropathy (IgAN), according to findings from a recent study.¹

Leveraging claims records for more than 4 million individuals in Japan, the study found greater event rates for IgAN in patients with chronic tonsillitis versus those without. Indeed, multivariable cause-specific analysis revealed chronic tonsillitis was associated with an increased risk of IgAN.¹

“Accumulating evidence demonstrated a significant association with IgAN and tonsils, especially in the East Asian population,” Kaori Hayashi, MD, professor of nephrology, endocrinology and metabolism at Keio University School of Medicine in Japan, and colleagues wrote.¹ “However, there have been no available epidemiologic data regarding the association between chronic tonsillitis history and the risk of IgAN.”

Although the exact cause of IgAN is unknown, various risk factors are thought to increase the chances of developing it, including age, sex, ethnicity, and family history. Timely diagnosis and treatment are important in the management of IgAN, but effective detection is challenging due to its frequent asymptomatic presentation, underscoring the need for a better understanding of risk factors potentially predisposing patients to developing IgAN.²

To examine the relationship between chronic tonsillitis and subsequent risk of developing IgAN, investigators conducted an observational cohort study using check-ups and insurance claims records drawn from a nationwide epidemiological dataset, JMDC Claims Database, from January 2005 to May 2022. For inclusion, patients were required to have undergone a health check-up for > 12 months after insurance enrollment. Exclusion criteria included a history of IgAN and missing values for smoking history, alcohol consumption, and physical activity.¹

In total, investigators identified 4,311,393 individuals who met the inclusion and exclusion criteria. Among the cohort, the median age was 44 (Interquartile range [IQR], 36-53) years and the majority of participants were male (57.9%). Chronic tonsillitis, defined based on ICD-10 diagnosis codes, was observed in 12,842 individuals (0.3%).¹

Investigators pointed out individuals with chronic tonsillitis were less likely to be male or have hypertension, diabetes mellitus, and dyslipidemia. Additionally, they noted smoking and alcohol consumption were less commonly observed in individuals with chronic tonsillitis.¹

During a median follow-up of 1089 (IQR, 532-1,797) days, 2653 IgAN events were documented. Overall, the event rate for IgAN was 1.75 (95% CI, 1.68-1.82) per 10,000 person-years.¹

Investigators observed a greater cumulative incidence of IgAN in individuals with chronic tonsillitis compared to their counterparts without chronic tonsillitis. Additionally, they noted the event rates for IgAN were increased in patients with chronic tonsillitis (4.93 per 10,000 person-years; 95% CI, 3.24-7.48) than in those without chronic tonsillitis (1.74 per 10,000 person-years; 95% CI 1.68-1.81). Multivariable cause-specific analysis revealed individuals with chronic tonsillitis had an elevated risk of developing IgAN (Hazard ratio [HR], 2.72; 95% CI, 1.79-4.14).¹

To assess whether the association between chronic tonsillitis and incident IgAN is specific to the tonsils, investigators analyzed the relationship between osteomyelitis and the risk of developing IgAN. In total, 5135 individuals had osteomyelitis and the incidence rate of IgAN was 1.76 (95% CI, 0.57-5.47) per 10,000 person-years in individuals with osteomyelitis compared to 1.75 (95% CI, 1.68-1.82) per 10,000 person-years in those without. Multivariable analysis showed the presence of osteomyelitis was not associated with incident IgAN (HR, 0.96; 95% CI, 0.31-2.99).¹

Investigators outlined potential limitations to these findings, including the working class population represented by the claims database used in the study leading to selection bias; the inability to account for all confounding factors; and lack of consideration for ethnic phenotypic differences of IgAN.¹

“Upon analyzing a nationwide epidemiological database, we identified an increased risk of IgAN incidence associated with chronic tonsillitis. This underscores the clinical significance of collaborative efforts between general physicians and nephrologists in the management of individuals with chronic tonsillitis,” investigators concluded.¹

References

1. ^{Nakayama T, Kaneko H, Suzuki Y, et al. Chronic Tonsillitis and IgA Nephropathy: Findings From a Nationwide Japanese Cohort Study. AJKD. doi:https://doi.org/10.1053/j.ajkd.2024.04.015}
2. ^{Mayo Clinic. IgA Nephropathy (Berger Disease). June 9, 2023. Accessed July 3, 2024. https://www.mayoclinic.org/diseases-conditions/iga-nephropathy/symptoms-causes/syc-20352268}