Performance of the ICD-10 coding algorithms for hyponatraemia using a serum sodium measurement as the reference standard
| Reference standard hyponatraemia (≤132 mmol/l) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Emergency department | Hospital admission | ||||||||
| ICD-10 E87.1 coding algorithms | + | − | Performance measures % | 95% CI | + | − | Performance measures % | 95% CI | |
| All diagnosis | + | 561 | 21 | Sn=7.53 | 6.96 to 8.16 | 964 | 207 | Sn=10.55 | 9.94 to 11.20 |
| Sp=99.96 | 99.94 to 99.98 | Sp=99.63 | 99.57 to 99.67 | ||||||
| − | 6885 | 57 114 | PPV=96.39 | 94.55 to 97.63 | 8171 | 55 157 | PPV=82.32 | 80.03 to 84.40 | |
| NPV=89.24 | 89.00 to 9.48 | NPV=87.10 | 86.83 to 87.36 | ||||||
| Main diagnosis | + | 309 | 11 | Sn=4.15 | 3.72 to 4.63 | ||||
| Sp=99.98 | 99.97 to 99.99 | ||||||||
| − | 7137 | 57 124 | PPV=96.56 | 93.95 to 98.07 | |||||
| NPV=88.89 | 88.65 to 89.13 | ||||||||
| Admission diagnosis | + | 773 | 90 | Sn=8.46 | 7.91 to 9.05 | ||||
| Sp=99.84 | 99.80 to 99.87 | ||||||||
| − | 8362 | 55 274 | PPV=89.57 | 87.35 to 91.44 | |||||
| NPV=86.86 | 86.59 to 87.12 | ||||||||
| Most responsible diagnosis | + | 251 | 4 | Sn=2.75 | 2.43 to 3.10 | ||||
| Sp=99.99 | 99.98 to 100.00 | ||||||||
| − | 8884 | 55 360 | PPV=98.43 | 96.04 to 99.39 | |||||
| NPV=86.17 | 85.90 to 86.44 | ||||||||
| Admission diagnosis+most responsible diagnosis | + | 248 | 4 | Sn=2.71 | 1.36 to 1.74 | ||||
| Sp=99.99 | 99.98 to 100.00 | ||||||||
| − | 8887 | 55 360 | PPV=98.41 | 95.99 to 99.38 | |||||
| NPV=86.17 | 74.99 to 75.66 | ||||||||
ICD-10, International Classification of Diseases, 10th revision; Sn, sensitivity; Sp, specificity; PPV, positive predictive value; NPV, negative predictive value; +, hyponatraemia yes; −, hyponatraemia no.