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Table 4 Predictive validity – identifying sick leaves lasting at least 26 weeks. Predictive validity of the ability to identify sick leaves lasting at least 26 weeks, using 8, 12 or 26 weeks, as cut-offs in length as predicted by the sick-listed, medical consultants or officers. Sensitivity, specificity, PPV and likelihood ratio data for NIO assessors are presented as means for length predicted on Sickness Certificates 1 and Sickness Certificates 2 (SC2).

From: Length of sick leave – Why not ask the sick-listed? Sick-listed individuals predict their length of sick leave more accurately than professionals

Predicted length n assess-ments Sensitivity (95% CI) Specificity (95% CI) Likelihood ratio (95% CI) PPV1 (95% CI) PPV adjusted to prevalence 17.9%(95% CI)
Sick-listed >= 8 weeks 152 0.69
(0.50–0.84)
0.69
(0.60–0.77)
2.2
(1.3–3.9)
0.37
(0.25–0.51)
0.33
(0.21–0.47)
Sick-listed >= 12 weeks 152 0.50
(0.32–0.68)
0.83
(0.75–0.90)
3.0
(1.5–6.1)
0.44
(0.28–0.62)
0.40
(0.24–0.58)
Sick-listed >= 26 weeks 152 0.28
(0.14–0.47)
0.98
(0.94–1.00)
16.9
(3.5–160)
0.82
(0. 48–0.98)
0.78
(0.44–0.95)
Consultants >= 8 weeks 1961 0.44
(0.39–0.49)
0.72
(0.70–0.74)
1.6
(1.3–1.9)
0.25
(0.22–0.29)
 
Consultants >= 12 weeks 1961 0.20
(0.16–0.24)
0.92
(0.90–0.93)
2.4
(1.8–3.2)
0.35
(0.28–0.41)
 
Consultants >= 26 weeks 1961 0.07
(0.04–0.10)
0.99
(0.98–0.99)
2.8
(1.5–5.4)
0.54
(0.38–0.69)
 
Officers >= 8 weeks 1968 0.55
(0.50–0.60)
0.58
(0.56–0.61)
1.3
(1.1–1.5)
0.22
19.3–24.9
 
Officers >= 12 weeks 1968 0.26
(0.21–0.31)
0.83
(0.81–0.85)
1.6
(1.3–2.0)
0.25
(0.20–0.29)
 
Officers >= 26 weeks 1968 0.06
(0.04–0.09)
0.98
(0.97–0.98)
1.5
(0.9–2.6)
0.34
(0.23–0.48)
 
SC2       
Consultants >= 12 weeks 637 0.89
(0.86–0.93)
0.29
(0.25–0.34)
1.3
(1.1–1.5)
0.44
(0.40–0.48)
0.22
(0.18–0.25)
Consultants >= 26 weeks 637 0.24
(0.19–0.29)
0.96
(0.93–0.98)
5.9
(3.4–11.0)
0.79
(0.68–0.87)
0.56
(0.41–0.70)
Officers >= 12 weeks 636 0.89
(0.85–0.93)
0.21
(0.17–0.25)
1.1
(0.9–1.3)
0.41
(0.37–0.45)
0.20
(0.16–0.23)
Officers >= 26 weeks 636 0.28
(0.22–0.34)
0.90
(0.87–0.93)
2.8
(1.9–4.3)
0.64
(0.54–0.73)
0.38
(0.28–0.49)
  1. 1The prevalence of sick leaves lasting at least 26 weeks was 21.1% in the responder group (n = 152), 17.9% for all the data (n = 993), and 38.5% in the SC2 group (n = 322).