CAPT.
| Methods | Method of allocation: treatment assignments were generated using a randomly permuted block method, stratified by clinical centre and using a randomly chosen block size. A member of the CAPT Co‐ordinating Centre reviewed an eligibility checklist with the local ophthalmologist and clinic co‐ordinator during a teleconference before disclosing which of the 2 eyes was assigned to laser treatment Masking: masked VA examiners. Unclear if participants and care providers were masked. Not reported if anatomic outcomes assessors were masked (i.e. Photograph Reading Centre), but masking was unlikely to be achieved since photocoagulation generates visible scars Exclusions after randomisation: none reported Losses to follow‐up: during 5 years of follow‐up, 5891 (97.2%) visits were completed of the 6061 6‐month and annual visits scheduled for surviving CAPT participants. This percentage was relatively stable over time Unusual study design: bilateral or paired study, i.e. 1 eye randomised to treatment or control and the fellow eye to the other study arm |
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| Participants | Country: US Number randomised: 1052 participants Enrolment period: May 1999 to March 2001 Age: mean 71 years Sex: 637 women (60.6%) Inclusion criteria: at least 10 drusen of size ≥ 125 μm within 3000 μm of FAZ centre; BCVA: 20/40 or more; aged ≥ 50 years Exclusion criteria: CNV or serous retinal PED in either eyes; geographic atrophy within 500 μm of FAZ centre; any ocular disease that might affect VA |
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| Interventions | Treatment: 60 burns in a grid pattern using a 100‐μm spot size, 0.1‐second duration and power to achieve a barely visible lesion. The burns were applied within an annulus between 1500 and 2500 μm from the FAZ centre Control: observation |
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| Outcomes | Primary: loss of ≥ 15 letters Secondary: change in VA; change in contrast sensitivity; change in critical print size; incidence of late AMD (CNV, serous PED, geographic atrophy) |
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| Notes | Since 2001, the participants were informed of the AREDS results and were left free to consume antioxidants Supported by the National Eye Institute, Bethesda, Maryland (grant nos: EY012211, EY012261, EY012279) COI declaration: the Manuscript Writing Team had no COI with regard to the material presented in the article |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Randomly permuted block method used, stratified by clinical centre and using a randomly chosen block size |
| Allocation concealment (selection bias) | Low risk | Eligibility assessed before randomisation and central allocation by telephone |
| Blinding (performance bias and detection bias) Development of CNV/geographic atrophy | Low risk | Unmasked study, but CNV occurrence was sufficiently objective as a diagnosis to be considered unbiased |
| Blinding (performance bias and detection bias) Measurement of vision | Low risk | Masked VA examiners, unclear if care providers were masked. Participants could not be masked since no sham procedure was mentioned |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | See Appendix 8. Throughout 5 years of follow‐up, 5891 (97.2%) visits were completed of the 6061 6‐month and annual visits scheduled for surviving CAPT participants. This percentage was relatively stable over time. In the updated version of this review, we considered missing data as no risk of bias in bilateral studies because a participant with paired treatment and control eyes is missed |
| Selective reporting (reporting bias) | Low risk | Development of CNV and atrophy, as well as loss of ≥ 3 lines of VA were well defined and relevant outcomes |
| Other bias | Unclear risk | Unclear |