Table 3.
Sensitivity, specificity, Youden index, predictive values, and likelihood ratios for different cut-off scores of the NRT and UPDRS30 with prospective falls and near falls as golden standards at Time 2 (n = 58).
| p-Value for ROC Analysis | Cut–Off Score | Sens (95% CI) | Spec (95% CI) | YI (95% CI) | PPV (95% CI) | NPV (95% CI) | LR+ (95% CI) | LR− (95% CI) | |
|---|---|---|---|---|---|---|---|---|---|
| Golden standard: falls (prevalence, 45%) | |||||||||
| NRT (0–3) |
0.034 | 1 | 0.48 (0.30–0.67) | 0.78 (0.61–0.89) | 0.26 (0.02–0.50) | 0.63 (0.46–0.79) | 0.66 (0.56–0.75) | 2.19 (1.01–4.75) | 0.67 (0.44–1.01) |
| 2 | 0.23 (0.11–0.42) | 0.91 (0.77–0.98) | 0.14 (−0.05–0.33) | 0.68 (0.28–0.95) | 0.59 (0.53–0.65) | 2.46 (0.68–8.90) | 0.85 (0.67–1.08) | ||
| 3 | 0.08 (0.02–0.24) | 1.00 (0.89–1.00) | 0.08 (−0.03–0.18) | 1.00 (0.13–1.00) | 0.57 (0.52–0.62) | NA (0.18–NA) | 0.92 (0.83–1.03) | ||
| UPDRS30 (0–4) |
0.079 | NA | |||||||
| Golden standard: falls and/or near falls (prevalence, 52%) | |||||||||
| NRT (0–3) |
0.043 | 1 | 0.45 (0.28–0.63) | 0.79 (0.61–0.90) | 0.23 (0.00–0.47) | 0.68 (0.50–0.83) | 0.58 (0.48–0.67) | 2.09 (0.92–4.73) | 0.70 (0.48–4.73) |
| 2 | 0.20 (0.10–0.37) | 0.89 (0.73–0.96) | 0.09 (−0.09–0.28) | 0.66 (0.27–0.91) | 0.51 (0.45–0.57) | 1.87 (0.52–6.76) | 0.90 (0.72–1.12) | ||
| 3 | 0.07 (0.02–0.21) | 1.00 (0.88–1.00) | 0.07 (−0.02–0.16) | 1.00 (0.15–1.00) | 0.50 (0.45–0.56) | NA (0.16–NA) | 0.93 (0.85–1.03) | ||
| UPDRS30 (0–4) |
0.231 | NA | |||||||
YI, Youden index; LR+/−, positive/negative likelihood ratio; NA, not applicable; NPV, negative predictive value; NRT, Nutt Retropulsion Test; PPV, positive predictive value; ROC, receiver operating characteristics; Sens, sensitivity; Spec, specificity; UPDRS30, item 30 of the Unified Parkinson’s Disease Rating Scale.