Along with the identification and approval of new drugs for the management of multiple sclerosis, there has been ever-increasing costs of treating the disease imposed on families and communities (45). Therefore, conducting economic evaluations seems necessary to identify the cheapest, most effective, and thus most cost-effective medicines and suggest them to doctors for prescription. Such studies can also help health policy makers to reduce patients’ out-of-pocket payments. To the knowledge of the researchers, this is one of the first health-economic studies conducted to compare Rituximab and NTZ in the treatment of multiple sclerosis. In fact, this is the first study carried out in Iran on the cost-effectiveness of Rituximab versus Natalizumab in MS patients.
According to the findings of this study, the mean annual costs of treatment with Natalizumab and Rituximab were $ 36,058.08 and $ 5,399.28, respectively. Thus, the mean cost of a course of treatment per patient was lower with Rituximab than with Natalizumab. One reason for this difference could be the higher price of Natalizumab compared to Rituximab. The studies by Chisari et al. (2021) showed that the annual cost of Rituximab was significantly lower than other approved drugs used in the treatment of MS (20). Hartung (2017) also showed that the annual cost of MS drugs was about $ 70,000 (46), which is consistent with the results of the present study.
The direct medical, direct non-medical, and indirect costs of Natalizumab were $ 34,912.80 (96.82% of the total costs), $ 665.70 (1.85% of the total costs), and $ 479.58 (1.33% of the total costs), respectively. However, the costs were 4,931.96 (91.34% of the total costs), 41.12 (0.76% of the total costs), and 426.20 (7.89% of the total costs) for Rituximab. Direct costs of both drugs accounted for most of the costs, the largest share of which was that of purchasing the main drug (94.36% and 41.33%, respectively). In this regard, the findings of this study are consistent with those of the studies conducted in Iran by Rezaei et al. (2019) (47) and Taheri et al. (2019) (48), and the ones carried out abroad by Dahham et al. (2021) (49), Brodszky et al. (2019) (50), Garcia et al. in Panama (2018) (51), and Ernstsson et al. (2016) (52).
The results of the present research showed that the highest utility rate and the lowest relapse rate in treatment with each drug was found in the patients with an EDSS of 0-2.5, and as disability increased, the life utility rate decreased and the relapse rate increased as well. This might be due to the fact that in higher EDSSs, the disease usually progresses and the patients’ limitations increase; so it is natural for the relapse rate to get higher and the utility rate to decrease (53, 54). In this respect, the results of this study are in line with the ones by Torgauten et al. (2021), Hellgren et al. (2020), Boremalm et al. (2019), and Yamout et al. (2018) (27, 55–57).
Based on the results of the Markov model analysis, the costs of Natalizumab and Rituximab were respectively $ 58,307.93 and $ 354,174.86, and the obtained QALYs were 7.77 and 7.65 over the lifetime horizon. Therefore, since Natalizumab had higher cost and lower QALY, it was considered the recessive option in cost-effectiveness analysis. Thus, Rituximab was more cost effective than Natalizumab.
Rezaei et al. (2019) conducted a study in Iran and examined the cost-utility of Natalizumab versus Fingolimod. They found out that the mean cost per patient during life was $ 58,751 in the Fingolimod arm and the utility was 8.09 QALY, but in the Natalizumab arm, the mean cost and the obtained QALY were $ 204,264 and $ 7.37, respectively. Thus, Natalizumab had higher cost and lower QALY and was the recessive option. This is consistent with the results of the present study (47).
In their study, Taheri et al. (2019) examined the cost-effectiveness of Alemtuzumab versus Natalizumab and concluded that the total discounted costs per patient were $ 147,417 and $ 150,579, respectively. In addition, the mean discounted QALYs were estimated at 7.07 and 6.05 for Alemtuzumab and Natalizumab, respectively, over a period of 20 years. Therefore, Natalizumab was the recessive option, which is consistent with the present study (48).
Walter et al. (2018) also evaluated the cost-utility of Alemtuzumab versus interferon beta, Fingolimod, and Natalizumab for relapsing multiple sclerosis in Austria and found that Alemtuzumab was the dominant option due to having higher total QALY (4.88) and lower total cost (€ 137.409) in comparison with interferon beta-1a (€ 200,133 and QALY of 4.38), Fingolimod (€ 240,903 and QALY of 4.64), and Natalizumab (€ 247.758 and QALY of 4.40). This is in line with the results of the present study (58).
In the study by Hettle et al. (2018) on the cost-effectiveness of Cladribine versus Alemtuzumab and Natalizumab in England, it was found that Cladribine was the dominant strategy over Alemtuzumab and Natalizumab when compared two by two, and quite dominant in the incremental analysis (i.e. they were cheaper and more effective). The total costs and QALYs discounted for Cladribine, Alemtuzumab, and Natalizumab were 92,484 and QALY 9,450, 104,136 and QALY 8,482, and 212,969 and QALY 7,739, respectively, which is consistent with the present study (32).
Montgomery et al. (2017) in the UK examined the cost-effectiveness of Fingolimod and Natalizumab and found that the cost of the former was £ 334897.93 and its obtained QALY was 6.18. However, the cost and QALY of the latter were £ 337501.15 and 6.35, respectively. The obtained ICER which was below the threshold in the UK (threshold ≥ 15313.06) showed that Fingolimod was the dominant option, and this is consistent with the present study (59).
The results of the one-way sensitivity analysis indicated that in the cost-utility analysis, the ICER value was negative and the highest sensitivity was to the price of Natalizumab, but considering that in the cost-utility sensitivity analysis the ICER value remained negative, the results of the study had required robustness. In addition, the results of probabilistic sensitivity analysis showed that Rituximab regimen was more cost-effective than Natalizumab and in all cases, it was in the acceptance area and below the threshold. Thus, it had obtained the best results in terms of the mentioned prices. The results also showed that doing sensitivity analysis did not change the status of Rituximab as the most effective drug regimen, suggesting the robust study results. In this regard, the present study is in line with those of Rezaei et al. (2019) and Taheri et al. (2019) in the country, and Walter et al. (2018), Hettle et al. (2018), and Montgomery et al. (2017) abroad (32, 47, 48, 58, 59).
One limitation of the present study was the self-reporting of the patients or their companions about direct non-medical and indirect costs, as they were likely to forget or approximate some of the costs. In addition, intangible costs were not calculated in this study due to the inability to measure them accurately