Impact of using the International Risk Scoring Tool on the cost-utility of palivizumab for preventing severe respiratory syncytial virus infection in Canadian moderate-to-late preterm infants

To assess the cost-utility of palivizumab <i>versus</i> no prophylaxis in preventing severe respiratory syncytial virus (RSV) infection in Canadian moderate-to-late preterm (32–35 weeks’ gestational age) infants using an (i) International Risk Scoring Tool (IRST) and (ii) Canadian RST (CRST). A decision tree was developed to assess cost-utility. Infants assessed at moderate- and high-risk of RSV-related hospitalization (RSVH) by the IRST or CRST received palivizumab or no prophylaxis and then progressed to either (i) RSVH; (ii) emergency room/outpatient medically attended RSV-infection (MARI) or (iii) were uninfected/non-medically attended. Infants admitted to intensive care could incur mortality (0.43%). Respiratory morbidity was accounted in all uninfected surviving infants for 6 years or 18 years (RSVH/MARI). Palivizumab efficacy (72.2% RSVH reduction) and hospital outcomes were from the Canadian CARESS, PICNIC and RSV-Quebec studies. Palivizumab costs (50 mg: CAN$752; 100 mg: $1,505) were calculated from Canadian birth statistics combined with a growth algorithm. Healthcare/payer and societal costs (May 2022; 1.5% discounting) were included. Cost <i>per</i> quality-adjusted life year (QALY) was $29,789 with the IRST (0.79 probability of being &lt;$50,000) and $15,833 with the CRST (0.96 probability). The model was most sensitive to utility scores, long-term sequelae and palivizumab cost. Vial sharing improved the incremental cost-utility ratio (IRST: $22,319; CRST: $9,231). Palivizumab was highly cost-effective (<i>vs</i> no prophylaxis) in Canadian moderate-to-late preterm infants using either the IRST or CRST. The IRST has fewer risk factors than the CRST (3 <i>vs</i> 7, respectively), captures more potential RSVHs (85% <i>vs</i> 54%) and provides another option to guide cost-effective RSV prophylaxis in Canada.本研究旨在对比帕利珠单抗（palivizumab）与不采取预防措施，在加拿大中度晚期早产（胎龄32~35周）婴儿中预防重度呼吸道合胞病毒（respiratory syncytial virus, RSV）感染的成本效用，分别采用(i)国际风险评分工具（IRST）与(ii)加拿大RST（CRST）开展评估。研究构建了决策树以开展成本效用分析：经IRST或CRST评估为RSV相关住院（RSVH）中高危的婴儿，将被分配接受帕利珠单抗预防或不预防，后续转归分为三类：(i)发生RSVH；(ii)因RSV感染就诊于急诊/门诊（医学关注型RSV感染，MARI）；(iii)未感染且未接受医学关注。入住重症监护室的婴儿可出现死亡，死亡率为0.43%。本研究对所有存活婴儿的呼吸道并发症按照6年或18年随访周期进行核算（针对RSVH/MARI转归者）。帕利珠单抗的疗效（可降低72.2%的RSVH发生率）及住院转归数据源自加拿大CARESS、PICNIC及RSV-Quebec三项研究。帕利珠单抗的用药成本（50mg规格：752加元；100mg规格：1505加元）基于加拿大出生统计数据结合生长算法测算得出。本研究纳入了医疗保健/支付方及社会层面的成本（核算时点为2022年5月，贴现率为1.5%）。每质量调整生命年（QALY）的成本为：采用IRST时29789加元（成本低于50000加元的概率为0.79），采用CRST时15833加元（成本低于50000加元的概率为0.96）。该模型对效用评分、长期后遗症及帕利珠单抗成本最为敏感。安瓿共享方案可优化增量成本效用比（IRST方案下为22319加元，CRST方案下为9231加元）。无论采用IRST还是CRST，帕利珠单抗预防方案对于加拿大中度晚期早产婴儿均具有极高的成本效用（相较于不预防方案）。相较于CRST，IRST的风险因素更少（分别为3项与7项），可识别更多潜在RSVH病例（占比分别为85%与54%），可为加拿大开展具有成本效用的RSV预防提供另一可选方案。