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. 2010 Jan;69(1):4–14. doi: 10.1111/j.1365-2125.2009.03537.x

Table 4.

Quality of the validation studies*

(A) (B) (C) (D)
Number of cases identified with study inclusion criteria Number of cases chosen to undergo validation Proportion of all cases identified with study inclusion criteria that were chosen to undergo validation Response rate to GP questionnaire/record request
Validation method n validations carried out Median (Range) n (%) validations where reported Median (Range) n (%) validations where reported Mean (Range) n (%) validations where reported Median (Range) n (%) validations where reported
Internal
Manual review of computerized records or diagnostic algorithm 31 1268 (50–78 172) 27 (87) 314 (57–61 097) 30 (97) 89.6 (0.12–100) 27 (87) n/a n/a
Sensitivity analysis 23 4732 (21–36 702) 19 (83) n/a n/a n/a n/a
External
Comparison of rates 143 1984 (5–200 000) 70 (49) n/a n/a n/a n/a
Additional information from GP 160 226 (1–51 688) 139 (87) 100 (1–3 010) 153 (96) 68.2 (0.15–100) 138 (86) 90.4 (55–100) 134 (83)
Questionnaire to GP only 43 1562 (10–51 688) 34 (79) 159 (10–2 040) 40 (93) 48.6 (0.39–100) 34 (79) 92.5 (55–100) 31 (72)
Questionnaire and record request to GP 39 51.5 (10–24 131) 36 (92) 40 (10–795) 38 (97) 78.9 (0.41–100) 36 (92) 90.4 (68–100) 35 (88)
Record request to GP only 78 199 (1–22 195) 69 (88) 88 (1–3 010) 75 (96) 72.3 (0.15–100) 68 (87) 90.0 (56–100) 68 (88)
Total 357 468 (1–200 000) 255 (71) 104 (1–61 097) 183 (96)* 71.0 (0.12–100) 165 (86) n/a n/a
*

For example, in an external validation of glaucoma [29], 24 131 glaucoma patients were identified based on the study inclusion criteria (column A). Of these patients, 100 were chosen to undergo validation by questionnaire and record request (column B). This means that the proportion of cases chosen to undergo validation was just 0.41% of the total (column C). Of these 100 cases, the GP responded in 95, giving a response rate of 95% (column D).