Table 3

Diagnostic performance characteristics for other thresholds of serum potassium values at presentation to an emergency department and at hospital admission

ICD-10 E87.5 coding algorithmEmergency departmentHospital admission (mmol/l)
>5>6>6.5>5>6>6.5
Per cent (95% CI)Per cent (95% CI)Per cent (95% CI)Per cent (95% CI)Per cent (95% CI) Per cent (95% CI)
All diagnosesSn6.55 (5.84 to 7.35)19.32 (16.73 to 22.21)21.81 (18.17 to 25.95)7.50 (6.83 to 8.22)23.34 (20.95 to 25.91)29.49 (25.76 to 33.51)
Sp99.98 (99.96 to 99.98)99.79 (99.76 to 99.83)99.70 (99.66 to 99.74)99.79 (99.75 to 99.82)99.56 (99.50 to 99.61)99.40 (99.34 to 99.46)
PPV94.74 (91.50 to 96.78)54.04 (48.23 to 59.73)32.98 (27.78 to 38.64)76.85 (73.11 to 80.21)48.15 (43.96 to 52.36)28.89 (25.23 to 32.85)
NPV94.01 (93.83 to 94.19)99.00 (98.92 to 99.07)99.48 (99.42 to 99.53)92.00 (91.78 to 92.20)98.66 (98.57 to 98.75)99.42 (99.35 to 99.47)
Main/most responsible diagnosisSn2.65 (2.20 to 3.18)8.53 (6.79 to 10.68)9.05 (6.69 to 12.13)1.16 (0.91 to 1.47)4.94 (3.81 to 6.37)7.94 (5.93 to 10.56)
Sp99.99 (99.97 to 99.99)99.92 (99.90 to 99.94)99.88 (99.85 to 99.90)99.99 (99.99 to 100)99.98 (99.97 to 99.99)99.96 (99.94 to 99.97)
PPV93.16 (87.09 to 96.49)58.12 (49.06 to 66.66)33.33 (25.44 to 42.28)95.52 (87.64 to 98.47)82.09 (71.25 to 89.45)62.69 (50.72 to 73.28)
NPV93.78 (93.59 to 93.96)98.87 (98.78 to 98.95)99.39 (99.33 to 99.45)91.51 (91.29 to 91.72)98.36 (98.26 to 98.45)99.24 (99.17 to 99.31)
Preadmit diagnosis5.84 (5.25 to 6.49)19.93 (17.69 to 22.38)25.71 (22.17 to 29.60)
99.92 (99.89 to 99.94)99.77 (99.73 to 99.80)99.63 (99.58 to 99.68)
87.30 (83.52 to 90.31)60.00 (54.93 to 64.86)36.76 (32.00 to 41.78)
91.87 (91.66 to 92.08)98.61 (98.52 to 98.70)99.39 (99.32 to 99.44)
  • ICD-10, International Classification of Diseases, 10th revision; NPV, negative-predictive value: PPV, positive-predictive value; Sn, sensitivity; Sp, specificity.