Table 3.
Validation statistics for Framingham Stroke Risk Score (FSRS), Stroke Riskometer™ and the Qstroke algorithm across all validation cohorts (ARCOS, RUSSIA and ROTTERDAM). Harrels C-statistic and Somer's D-statistic to measure discrimination (the ability of the algorithms to discriminate between stroke and nonstroke events). C-statistic values of 0·50 represent chance and 1 denotes the ability of the risk score to discriminate perfectly. D-statistics over 0·10 indicate that the risk score has a good ability to differentiate between an event and nonevent. AUROC = Area Under the Receiver operating characteristics Curve (AUROC) with 95% confidence intervals. R2 statistic was calculated to indicate the level of variability accounted for by each prediction algorithm
| Algorithm | Year | Statistic | ARCOS | RUSSIA | ROTTERDAM | |||
|---|---|---|---|---|---|---|---|---|
| Mean (95% CI) | Mean (95% CI) | Mean (95% CI) | ||||||
| Males | Females | Males | Females | Males | Females | |||
| FSRS | 5 | R2 (%) | 49·85 (49·73–50·08) | 49·90 (49·88–49·92) | 0·99 (0·08–3·14) | 0·32 (0·001–1·54) | 0·72 (0·21–1·81) | 1·85 (0·89–3·40) |
| C statistic | Stroke event data only | 0·515 (0·514–0·516) | 0·506 (0·505–0·506) | 0·511 (0·511–0·511) | 0·511 (0·511–0·512) | |||
| D statistic | 0·030 (0·029–0·031) | 0·011 (0·011–0·011) | 0·022 (0·021–0·022) | 0·023 (0·023–0·023) | ||||
| AUROC | 68·1 (58·5–77·7) | 60·1 (49·1–72·0) | 63·0 (57·9–68·0) | 64·7 (60·1–69·4) | ||||
| 10 | R2 (%) | 0·91 (0·34–1·85) | 2·05 (1·17–3·23) | |||||
| C statistic | 0·518 (0·517–0·518) | 0·521 (0·521–0·521) | ||||||
| D statistic | 0·035 (0·035–0·035) | 0·042 (0·042–0·043) | ||||||
| AUROC | 61·2 (57·6–64·8) | 64·2 (61·0–67·3) | ||||||
| Stroke Riskometer™ | 5 | R2 (%) | 49·85 (49·73–50·08) | 49·90 (49·88–49·92) | 0·99 (0·08–3·14) | 0·32 (0·001–1·54) | 0·72 (0·21–1·81) | 1·85 (0·89–3·40) |
| C statistic | Stroke event data only | 0·515 (0·514–0·516) | 0·514 (0·513–0·514) | 0·511 (0·511–0·511) | 0·513 (0·512–0·513) | |||
| D statistic | 0·030 (0·029–0·031) | 0·029 (0·028–0·029) | 0·022 (0·022–0·023) | 0·027 (0·026–0·027) | ||||
| AUROC | 68·1 (58·5–77·7) | 77·4 (69·2–85·6) | 63·6 (58·5–68·5) | 65·4 (61·0–69·7) | ||||
| 10 | R2 (%) | 0·91 (0·34–1·85) | 0·91 (0·34–1·85) | |||||
| C statistic | 0·517 (0·517–0·517) | 0·522 (0·521–0·522) | ||||||
| D statistic | 0·033 (0·032–0·033) | 0·045 (0·044–0·045) | ||||||
| AUROC | 60·4 (58·8–64·0) | 64·6 (61·6–67·6) | ||||||
| QStroke | 5 | R2 (%) | 49·79 (49·73–50·3) | 49·98 (49·88–50·04) | 5·22 (1·54–14·22) | 2·49 (0·24–9·77) | 1·04 (0·43–2·13) | 1·26 (0·60–2·36) |
| C statistic | Stroke event data only | 0·526 (0·524–0·527) | 0·511 (0·511–0·512) | 0·513 (0·513–0·513) | 0·515 (0·515–0·515) | |||
| D statistic | 0·051 (0·050–0·052) | 0·023 (0·022–0·023) | 0·027 (0·027–0·027) | 0·031 (0·030–0·031) | ||||
| AUROC | 80·6 (72·3–88·9) | 71·2 (59·2–83·8) | 66·1 (61·9–70·2) | 69·7 (66·3–73·1) | ||||
| 10 | R2 (%) | 0·97 (0·41–1·92) | 0·97 (0·41–1·92) | |||||
| C statistic | 0·520 (0·519–0·520) | 0·526 (0·526–0·526) | ||||||
| D statistic | 0·039 (0·039–0·039) | 0·053 (0·053–0·053) | ||||||
| AUROC | 62·5 (59·4–65·7) | 67·6 (65·0–70·1) | ||||||