Table 3.
Characteristics of costs reported by 138 included studies reporting costs associated with VI and its major causes.
| General VI studies |
Condition-specific studies |
Total |
||||
|---|---|---|---|---|---|---|
| n | % | n | % | n | % | |
| Number of reported costs components (n = 202)a | ||||||
| Direct costs | 28 | 39% | 87 | 66% | 115 | 57% |
| Productivity loss costs | 19 | 27% | 18 | 14% | 37 | 18% |
| Informal care costs | 14 | 20% | 16 | 12% | 30 | 15% |
| Intangible costs | 10 | 14% | 10 | 8% | 20 | 10% |
| Method of resource quantification (n = 138)b | ||||||
| Top down (population-level) | 14 | 37% | 10 | 10% | 24 | 17% |
| Bottom up (person-based) | 20 | 53% | 83 | 83% | 103 | 75% |
| Top down and bottom up | 4 | 10% | 4 | 4% | 8 | 6% |
| Not applicable c | 0 | 0% | 3 | 3% | 3 | 2% |
| Level of reporting estimates (n = 138)d | ||||||
| Projected to a population (e.g. region, country) | 20 | 53% | 19 | 19% | 39 | 28% |
| Recruited sample (e.g. average cost per patient or per treatment, excess cost) | 16 | 42% | 80 | 80% | 96 | 70% |
| Both | 2 | 5% | 1 | 1% | 3 | 2% |
| Use of discounting (n = 138) | ||||||
| Yes | 6 | 16% | 21 | 21% | 27 | 20% |
| No | 0 | 0% | 0 | 0 | 0 | 0% |
| Not applicable e | 32 | 84% | 79 | 79% | 111 | 80% |
| Method use to deal with uncertainty (n = 138) | ||||||
| Sensitivity analysis | 13 | 34% | 28 | 28% | 41 | 30% |
| None | 25 | 66% | 72 | 72% | 97 | 70% |
Studies reported more than one cost component therefore the sum of studies distributed by type of cost reported (n = 202) is greater than the number of studies (n = 138);
Top-down method uses aggregate expenditures by cost component while bottom-up method assigns costs to individuals with a specific disease or condition;
Includes 1 study that examined the relationship between vision impairment from cataract with time use (including paid work), 1 study that described the burden (measured with EQ5D Health States) of bilateral age-related macular degeneration and 1 study that reported impact on caregivers measured in number of work days lost;
Population estimates provide information about the costs incurred in a defined population (district country, subregion, global) during a specific period of time. Average cost estimates provide information about the cost per patient or per treatment incurred in a specific population during a specific period of time;
Discounting is only applicable in studies that report costs and consequences for multiple years.