Treat and extend regimen for diabetic macular oedema-a systematic review and meta-analysis

Various treatment regimens are currently practiced in the treatment of CI-DMO (centre-involving diabetic macular oedema). In recent years, there has been a growing body of evidence supporting a treat and extend (T&E) regimen for DMO which offers the promise of comparable visual and anatomical outcomes while reducing injection burden. This meta-analysis was hence performed to evaluate the aforementioned outcomes in the treatment of DMO. Ten studies met the inclusion criteria.

A search of PubMed, MEDLINE, Current Contents, and Cochrane Central Register of Controlled Trials (CENTRAL) databases was performed. We employed the terms 'treat AND extend AND (diabetic AND macular AND edema OR oedema)' to ensure a comprehensive search. The search workflow adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

The pooled analysis of the mean number of injections in 1 year for T&E-aflibercept (AFL), T&E-ranibizumab (RBZ) and collectively was 9.1 (95% CI: 7.63-10.63), 10.0 (95% CI: 9.55-10.47) and 9.6 (95% CI: 8.62-10.49), respectively. Improvements in vision at 1 year for T&E-AFL, T&E-RBZ and collectively were 6.26 (95% CI: 3.24-9.29), 7.14 (95% CI: 4.76-9.52) and 7.08 (95% CI: 5.32-8.84) letters, respectively. The improvements in central subfield thickness at 1 year for T&E-AFL, T&E-RBZ and collectively were 131.94 (95% CI: 100.29-163.60), 108.64 (95% CI: 82.82-134.46) and 121.32 (95% CI: 102.89-139.75) microns, respectively.

The meta-analysis of T&E for DMO did not show a clear advantage in reducing the number of injections compared to landmark clinical trials with pro-re-nata (PRN) treatment regimens in the first year of treatment with limited gains in visual and anatomical outcomes. However, the T&E approach offers the potential for fewer patient visits, thereby reducing treatment burden. Longer term studies on T&E with a standardised protocol would be required to assess the longevity of the vision gain in the first year despite a likely reduced treatment burden compared to the PRN trials.