Table 2. Reporting of STROBE items in 89 blindness prevalence surveys published between January 2008 and March 31 2016.
| STROBE Item | STROBE Description | Question answered | Individual component adequate | Overall item adequate* n (%) | ||
|---|---|---|---|---|---|---|
| NA | No | Yes | ||||
| Abstract | ||||||
| 1a | Indicate the study’s design with a commonly used term in the title or the abstract | Is the design referred to as either ‘cross-sectional’ or ‘population-based survey’ in the title or abstract? | - | 40 (45) | 49 (55) | 49 (55) |
| 1b | Provide in the abstract an informative and balanced summary of what was done and what was found | Does the abstract provide an informative summary of what was done and found? | 1 (1) | 3 (3) | 85 (96) | 85 (97) |
| Introduction | ||||||
| 2 | Explain the scientific background and rationale for the investigation being reported | Is the scientific background and rationale for the investigation reported? | - | 4 (4) | 85 (96) | 85 (96) |
| 3 | State specific objectives, including any pre-specified hypotheses | Are objectives and /or hypotheses reported? | - | 1 (1) | 88 (99) | 88 (99) |
| Methods | ||||||
| 4 | Present key elements of study design early in the paper | Are the key elements of the study design presented before the end of methods? | - | 8 (9) | 81 (91) | 81 (91) |
| 5 | Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection | Are the setting/locations reported? | - | 6 (7) | 83 (93) | 71 (80) |
| Are the dates of the survey reported? | - | 13 (15) | 76 (85) | |||
| 6 | Give the eligibility criteria, and the sources and methods of selection of participants | Are eligibility criteria, and sources and methods of selection of participants provided? | - | 7 (8) | 82 (92) | 82 (92) |
| 7 | Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable | Is the outcome (i.e. blindness) defined in the introduction or methods, or the 1st time it is mentioned in results (e.g. <3/60 in the better eye)? | - | 7 (8) | 82 (92) | 28 (31) |
| Are diagnostic criteria for blindness described (i.e. how many letters on the line were correct/incorrect to be allocated to that level of vision)? | - | 60 (67) | 29 (33) | |||
| 8 | For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group | Is vision assessment described (in sufficient detail to be replicated)? | - | 49 (55) | 40 (45) | 24 (27) |
| If blindness is reported by age groups, is the method by which age was ascertained described? | 32 (36) | 38 (43) | 19 (21) | |||
| If blindness is reported by another social variable (e.g. education), is the method by which this was ascertained described? | 54 (61) | 20 (22) | 15 (17) | |||
| 9 | Describe any efforts to address potential sources of bias | Was there any effort to address potential sources of: | - | 23 (26) | 66 (74) | 33 (37) |
| –selection bias when selecting clusters? | ||||||
| –selection bias when selecting individuals within clusters? | - | 31 (35) | 58 (65) | |||
| –measurement bias? (e.g. inter-rater agreement) | - | 45 (51) | 44 (49) | |||
| 10 | Explain how the study size was arrived at | Was the method of establishing the study size explained AND the calculated size provided? | - | 29 (33) | 60 (67) | 60 (67) |
| 11 | Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why | Did they explain how quantitative variables were handled in the analysis? | - | 46 (52) | 43 (48) | 43 (48) |
| 12a | Describe all statistical methods, including those used to control for confounding | Were statistical methods for calculating blindness prevalence described? | - | 48 (54) | 41 (46) | 41 (46) |
| 12b | Describe any methods used to examine subgroups and interactions | If analysis is undertaken to compare blindness in subgroups, is the analysis explained in methods? | 48 (54) | 13 (15) | 28 (31) | 28 (68) |
| 12c | Explain how missing data were addressed | (In the methods) is it reported how missing data were addressed? | - | 86 (97) | 3 (3) | 3 (3) |
| 12d | If applicable, describe analytical methods taking account of sampling strategy | If age standardization is reported in results, is the process explained in methods? | 49 (55) | 26 (29) | 14 (16) | 14 (34) |
| Results | ||||||
| 13a | Report numbers of individuals at each stage of study | Are the number of people enumerated and the number examined provided? | - | 12 (13) | 77 (87) | 77 (87) |
| 13b | Give reasons for non-participation at each stage | Are the reasons for non-participation provided? | - | 50 (56) | 39 (44) | 39 (44) |
| 13c | Consider use of a flow diagram† | Was a flow diagram used? | 87 (98) | - | 2 (2) | - |
| 14a | Give characteristics of study participants (eg demographic, clinical, social) | Were participants described by (at least) age and sex? | - | 9 (10) | 80 (90) | 80 (90) |
| 14b | Indicate number of participants with missing data for each variable of interest | Are the number of participants with missing vision data reported (or can we tell from the data presented)? | - | 60 (67) | 29 (33) | 29 (33) |
| 15 | Report numbers of outcome events or summary measures | Are the number of blind participants reported? | - | 8 (9) | 81 (91) | 81 (91) |
| 16a | Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence interval). | Did they report [unadjusted and/or adjusted prevalence estimate] AND 95%CI? | 1 (1)‡ | 14 (16) | 74 (83) | 74 (84) |
| 17 | Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses | Was any analysis undertaken to compare blindness in subgroups? | 1 (1)‡ | 48 (54) | 40 (45) | 40 (45) |
| Discussion | ||||||
| 18 | Summarise key results with reference to study objectives | Are key results summarised with reference to the study objectives? | - | 9 (10) | 80 (90) | 80 (90) |
| 19 | Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias | Did they discuss the limitations of the study, taking into account sources of potential bias/ imprecision (both direction and magnitude) in relation to: –sample selection/representativeness; |
- | 70 (79) | 19 (21) | 15 (17) |
| –other sources of potential bias or imprecision | - | 48 (54) | 41 (46) | |||
| 20 | Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence | Did they provide an overall interpretation of results considering objectives, analyses, results from similar studies and other relevant evidence? | - | 5 (6) | 84 (94) | 84 (94) |
| 21 | Discuss the generalisability (external validity) of the study results | Did they discuss the generalisability (external validity) of the study results? | - | 62 (70) | 27 (30) | 27 (30) |
| 22 | Give the source of funding and the role of the funders for the present study | Is the funding source provided? | - | 20 (22) | 69 (78) | 20 (22) § |
| Is the role of the funder provided? | 6 (7) | 69 (78) | 14 (17) | |||
Items 12e, 16b, 16c removed a priori as they were considered not applicable to reporting blindness prevalence surveys.
*to be assessed as a yes, individual components must be assessed as yes; NA not included; proportion (%) = yes/(yes+no).
† as enumeration and participation were the only stages involved, we categorized this as yes or NA.
‡ one study found no blind participants (only vision impaired) so could not report this.
§ The role of funders was NA for 6 studies that received no specific funding; these studies were included in the numerator for the overall assessment of this item.