Characterizing the clinical and economic burden of COVID-19 among individuals with immunocompromising conditions in Ontario, Canada – a matched, population-based observational study

COVID-19 continues to be associated with substantial burden among immunocompromised patients (IC). This study aimed to describe and compare outcomes during and following COVID-19 hospitalizations among IC and non-IC patients.
Patients hospitalized with COVID-19 (January 2020–March 2023) were identified in Ontario health administrative claims databases. All eligible IC (≥1 of solid organ or stem cell transplant; hematological malignancy; rheumatoid arthritis; multiple sclerosis; or primary immunodeficiency) were matched (1:4) to eligible non-IC. Clinical, resource, and costburden were assessed during and post-hospitalization. Multivariate regression models were used to estimate relative risks (RRi), rates (RRa), and corresponding 95% confidence intervals (CIs), adjusting for neighborhood deprivation, long-term care residency, baseline comorbidities, and COVID-19 vaccination status.
9,283 IC hospitalized (mean age 68.7 years; 52.1% female) were matched to 37,127 non-IC. During index hospitalization, IC had greater risks of intensive care unit admission (RRi = 1.06 [1.01–1.12]), ventilation (RRi = 1.27 [1.19–1.36]), and all-cause mortality (RRi = 1.34 [1.27–1.41]) compared to non-IC. Within 30-days post-discharge, IC had greater rates of all-cause readmission (RRa = 1.33 [1.26–1.40]), emergency departments admission (RRa = 1.13 [1.08–1.18]), home oxygen use (RRi = 1.35 [1.15–1.58]), and COVID-19-related rehabilitation (RRa = 1.52 [1.22–1.89]), resulting in 21% (16%–25%) and 51% (45%–58%) greater costs in hospital and post-discharge, respectively. All-cause mortality remained approximately 5% higher for IC vs. non-IC at 30- and 60-days post-discharge (p < .001). Resource use remained elevated among IC with 57% (50%–64%) greater costs within 180 days post-discharge.
Unmeasured confounding remains; hospital prescription data were not available such that treatments for COVID-19 were not captured. Attribution of post-discharge resource use and costs to COVID-19 was subject to greater uncertainty further from the index hospitalization.
IC experienced more severe COVID-19 hospitalization outcomes compared to non-IC. COVID-mitigating policies and prophylactic treatments are needed to protect immunocompromised populations.

新型冠状病毒肺炎（COVID-19）仍与免疫功能低下患者（immunocompromised patients，以下简称IC）的沉重疾病负担密切相关。本研究旨在描述并对比免疫功能低下患者与非免疫功能低下患者在新冠住院期间及出院后的转归情况。
研究对象为2020年1月至2023年3月期间在安大略省卫生行政索赔数据库中识别出的新冠住院患者。将符合纳入标准的IC患者（需满足实体器官或干细胞移植、血液系统恶性肿瘤、类风湿关节炎、多发性硬化症或原发性免疫缺陷病中至少1项）按照1:4的比例匹配至符合条件的非IC患者。评估住院期间及出院后的临床结局、医疗资源利用情况与成本负担。采用多因素回归模型估算相对风险（relative risks，RRi）、发生率（rates，RRa）及对应的95%置信区间（confidence intervals，CIs），校正因素包括社区贫困程度、长期护理机构居住情况、基线合并症及新冠疫苗接种状态。
最终纳入9283例IC住院患者（平均年龄68.7岁；女性占比52.1%），并匹配得到37127例非IC患者。在本次住院期间，与非IC患者相比，IC患者的重症监护病房入住风险（相对风险RRi=1.06[95%CI:1.01–1.12]）、机械通气风险（RRi=1.27[95%CI:1.19–1.36]）及全因死亡率（RRi=1.34[95%CI:1.27–1.41]）均显著升高。出院后30天内，IC患者的全因再入院率（RRa=1.33[95%CI:1.26–1.40]）、急诊就诊率（RRa=1.13[95%CI:1.08–1.18]）、家庭氧疗使用率（RRi=1.35[95%CI:1.15–1.58]）及新冠相关康复治疗率（RRa=1.52[95%CI:1.22–1.89]）均更高，对应的住院期间及出院后成本分别增加21%（16%–25%）与51%（45%–58%）。出院后30天及60天时，IC患者的全因死亡率仍较非IC患者高约5%（p<0.001）。IC患者的医疗资源利用水平持续偏高，出院后180天内的成本较非IC患者高出57%（50%–64%）。
本研究仍存在未测量混杂因素的局限；由于未获取医院处方数据，无法记录新冠治疗相关信息。且随着出院时间延长，将出院后医疗资源利用及成本归因于新冠感染的不确定性也随之增加。
与非IC患者相比，IC患者的新冠住院治疗结局更为严重。因此，需制定新冠防控政策及预防性治疗方案以保护免疫功能低下人群。