Introduction Respiratory inflammation has been proposed as a risk factor for MS. This study aims to determine if hospital-diagnosed pneumonia in adolescence (before age 20 years) is associated with subsequent multiple sclerosis (MS). Methods This case-control study included incident MS cases after age 20 years identified using the Swedish national registers. Cases were matched with 10 general population controls by age, sex and region. Pneumonia diagnoses were identified between 0–5, 6–10, 11–15 and 16–20 years of age. Conditional logistic regression models adjusted for infectious mononucleosis (IM) and education calculated ORs with 95% CIs. Urinary tract infections (UTIs), a common complication of MS, before age 20 years were included as a control diagnosis for reverse causation. Results There were 6109 cases and 49 479 controls included. Pneumonia diagnosed between age 11–15 years was associated with subsequent MS (adj OR 2.00, 95% CI 1.22 to 3.27). Although not statistically significant, sensitivity analyses showed similar magnitude associations of pneumonia between age 11–15 years and MS. No statistically significant associations with MS for pneumonia at other age groups were observed. Adjustment for IM had no notable effect on associations, but was statistically significantly associated with MS. UTIs were not associated with MS. Conclusion Pneumonia at 11–15 years of age was associated with MS, suggesting a possible role for inflammation of the respiratory system in the aetiology of MS during a period of susceptibility in adolescence. Further research on respiratory infections prior to MS onset should be conducted to replicate this finding and determine explanatory causal mechanisms.

中文翻译：

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医院在 20 岁之前诊断出肺炎和多发性硬化风险

引言 呼吸道炎症已被认为是 MS 的危险因素。本研究旨在确定青春期（20 岁之前）医院诊断的肺炎是否与随后的多发性硬化症 (MS) 相关。方法 本病例对照研究包括使用瑞典国家登记册确定的 20 岁后的 MS 病例。病例按年龄、性别和地区与 10 名普通人群对照匹配。在 0-5、6-10、11-15 和 16-20 岁之间确定了肺炎诊断。针对传染性单核细胞增多症 (IM) 和教育调整的条件逻辑回归模型计算了具有 95% CI 的 OR。尿路感染 (UTI) 是 MS 的常见并发症，在 20 岁之前被包括作为反向因果关系的对照诊断。结果共纳入病例6109例，对照组49479人。在 11-15 岁之间诊断出的肺炎与随后的 MS 相关（adj OR 2.00, 95% CI 1.22 至 3.27）。尽管没有统计学意义，但敏感性分析显示 11-15 岁之间的肺炎与 MS 的相关程度相似。没有观察到其他年龄组的肺炎与 MS 的统计学显着关联。IM 的调整对关联没有显着影响，但与 MS 具有统计学显着相关性。UTI 与 MS 无关。结论 11-15 岁的肺炎与 MS 相关，提示呼吸系统炎症可能在青春期易感期 MS 的病因中发挥作用。