Original Title: Eficacia, seguridad y eficiencia de dispositivos de drenaje subconjuntival con aproximación ab-interno para cirugía del glaucoma primario de ángulo abierto

Authors' objectives: To analyse effectiveness-efficacy, safety, efficiency and other aspects related to the patient values and preferences regarding the XEN®45 implant compared to trabeculectomy in the treatment of primary open-angle glaucoma, and also to draw evidence-based conclusions for use in clinical practice.

Authors' results and conclusions: In the clinical effectiveness and safety-based SR, two monocentric observational studies were gathered, of moderate methodological quality. Overall, these studies included a total of 332 participants with either XEN®45 or a trabeculectomy, who were monitored for 12 and 24 months post-operation, respectively. Both the reduction in IOP and the number of drugs taken post-surgery are better in groups who underwent a trabeculectomy. In terms of safety, only one study collected results on side effects, which were more common in patients who underwent a trabeculectomy. The exception was patients with hypotonia and choroidal detachment, which were more frequent in those who had XEN®45 surgery. The systematic review of economic assessment did not find any study which met inclusion criteria. For the planned 15-year horizon, the Cost Utility Analysis (CUA) obtained 7.75 quality-adjusted life years (QALY) with XEN®45, compared to 7.51 QALY with a conventional trabeculectomy. From the perspective of the SNHS, the Incremental Cost-Utility Ratio (ICUR) for XEN®45 to trabeculectomy was €5,887/QALY, with the microinvasive technique a predominant option. Deterministic sensitivity analyses impacted the results when the visual field deficiency variable was changed at the beginning. However, upon carrying out the Monte Carlo simulations, more than 60% of predominant results were obtained for XEN®45, compared to the trabeculectomy strategy. In terms of aspects relating to patient values and preferences, a transversal, monocentric comparative study of moderate methodological quality was utilised. The study assessed and compared the health-related quality of life (HRQL) of 34 patients (17 underwent XEN®45 and 17 underwent a trabeculectomy) and its relationship with other clinical variables. HRQL was slightly worse, but not statistically significant, in patients who underwent XEN®45, as these patients reported more symptoms. A statistically significant negative correlation was seen between score on the Glaucoma Symptom Scale (GSS) questionnaire, consisting of 10 questions about visual and non-visual eye symptoms, and IOP, but there was no linking causality found between the two. The trabeculectomy could be a safer technique than XEN®45 implant insertion and could contribute to a greater reduction in IOP and the number of drugs taken post-surgery in the 12- and 24-month post-treatment period. The only observation is that it carries a higher risk of hypotonia and choroidal detachment in the 12 months post-surgery. That said, the XEN®45 approach is a more cost-effective strategy than the trabeculectomy, being a predominant option from the perspective of the SNHS in a 15-year period. However, there is a degree of uncertainty about these findings, as until now, there have been few studies on the topic which compare both techniques, and the quality of existing evidence is moderate-low. In addition, the results obtained from the economic model are subject to variation, in line with real clinical practice conditions.

Authors' recommendations: In the clinical effectiveness and safety-based SR, two monocentric observational studies were gathered, of moderate methodological quality. Overall, these studies included a total of 332 participants with either XEN®45 or a trabeculectomy, who were monitored for 12 and 24 months post-operation, respectively. Both the reduction in IOP and the number of drugs taken post-surgery are better in groups who underwent a trabeculectomy. In terms of safety, only one study collected results on side effects, which were more common in patients who underwent a trabeculectomy. The exception was patients with hypotonia and choroidal detachment, which were more frequent in those who had XEN®45 surgery. The systematic review of economic assessment did not find any study which met inclusion criteria. For the planned 15-year horizon, the Cost Utility Analysis (CUA) obtained 7.75 quality-adjusted life years (QALY) with XEN®45, compared to 7.51 QALY with a conventional trabeculectomy. From the perspective of the SNHS, the Incremental Cost-Utility Ratio (ICUR) for XEN®45 to trabeculectomy was €5,887/QALY, with the microinvasive technique a predominant option. Deterministic sensitivity analyses impacted the results when the visual field deficiency variable was changed at the beginning. However, upon carrying out the Monte Carlo simulations, more than 60% of predominant results were obtained for XEN®45, compared to the trabeculectomy strategy. In terms of aspects relating to patient values and preferences, a transversal, monocentric comparative study of moderate methodological quality was utilised. The study assessed and compared the health-related quality of life (HRQL) of 34 patients (17 underwent XEN®45 and 17 underwent a trabeculectomy) and its relationship with other clinical variables. HRQL was slightly worse, but not statistically significant, in patients who underwent XEN®45, as these patients reported more symptoms. A statistically significant negative correlation was seen between score on the Glaucoma Symptom Scale (GSS) questionnaire, consisting of 10 questions about visual and non-visual eye symptoms, and IOP, but there was no linking causality found between the two. The trabeculectomy could be a safer technique than XEN®45 implant insertion and could contribute to a greater reduction in IOP and the number of drugs taken post-surgery in the 12- and 24-month post-treatment period. The only observation is that it carries a higher risk of hypotonia and choroidal detachment in the 12 months post-surgery. That said, the XEN®45 approach is a more cost-effective strategy than the trabeculectomy, being a predominant option from the perspective of the SNHS in a 15-year period. However, there is a degree of uncertainty about these findings, as until now, there have been few studies on the topic which compare both techniques, and the quality of existing evidence is moderate-low. In addition, the results obtained from the economic model are subject to variation, in line with real clinical practice conditions.

Authors' methods: This report has been created in line with the Guideline for the Elaboration and Adaptation of Rapid Health Technology Assessment (HTA) Reports from the Spanish Network of Agencies for Health Technology Assessment and Services of the Spanish National Health System (RedETS), as well as GRADE methodology (Grading of Recommendations, Assessment and Evaluation). There were three systematic reviews (SR) of literature: clinical effectiveness and safety; economic evaluations; and aspects relating to the values and preferences of patients, in this case, with regard to the XEN®45 Gel Stent subconjunctival drainage device for patients with POAG. A costs and results simulation was performed using a three-phase Markov model (including the Death phase), in which patients traverse a monthly cycle. The effectiveness data driving this transition through the cycle were obtained from the studies reviewed in this report. A 15-year temporal horizon was adopted, approximately a lifetime model, and a discount rate of 3%. We consider the perspective of the Spanish National Health System (SNHS), which is why only direct costs were taken into consideration (surgical interventions, post-surgery complications, medication used throughout consultation and analysis period or follow-up tests). The robustness of the model was ensured using a deterministic and probabilistic analysis

Project Status: Completed

Year Published: 2023

URL for published report: https://doi.org/10.46994/ets_23

English language abstract: An English language summary is available

Publication Type: Mini HTA

Country: Spain

DOI: https://doi.org/10.46994/ets_23

Organisation Name: Health Sciences Institute in Aragon (IACS)

Contact Address: Avda, San Juan Bosco, 13, planta 2

Contact Name: María Pilar Calvo Pérez

Contact Email: direccion.iacs@aragon.es