Skip to main content

Table 3 Encounter characteristics associated with accuracy of syndrome definitions based on physician claims (OR >1.00 means the encounter characteristic increased the PPV of the syndrome definition, OR < 1.00 means the encounter characteristic reduced the PPV)

From: Patient, physician, encounter, and billing characteristics predict the accuracy of syndromic surveillance case definitions

  No. visits with a syndrome-positive physician claim Bivariate regression analysis Multivariate regression analysis1
Encounter characteristics Syndrome-positive in the chart
(N = 2,967)
Syndrome-negative in the chart
(N = 1,363)
Total
(N = 4,330)
OR 95% CI P value OR 95% CI P value
  No. % No. % No. %       
Syndrome type:             
   Fever 371 12.5 230 16.9 601 13.9 Ref. Ref. Ref. Ref. Ref. Ref.
   Gastrointestinal 572 19.3 283 20.8 855 19.8 1.57 (1.25, 1.97) < 0.0001 1.72 (1.36, 2.16) < 0.0001
   Neurological 608 20.5 363 26.6 971 22.4 1.29 (1.05, 1.60) 0.02 1.38 (1.11, 1.72) < 0.01
   Rash 628 21.2 269 19.7 897 20.7 1.80 (1.44, 2.25) < 0.0001 1.89 (1.51, 2.37) < 0.0001
   Respiratory 808 27.2 241 17.7 1049 24.2 1.72 (1.36, 2.17) < 0.0001 1.66 (1.29, 2.14) < 0.0001
   ILI 555 18.7 98 7.2 653 15.1 2.98 (2.32, 3.82) < 0.0001 2.68 (2.06, 3.48) < 0.0001
Type of clinic:             
   Private clinic 2,916 98.3 1,320 96.9 4,236 97.8 Ref. Ref. Ref. Ref. Ref. Ref.
   Community health center 10 0.3 8 0.6 18 0.4 0.58 (0.14, 2.35) 0.45 0.46 (0.11, 2.01) 0.30
   Hospital-based ambulatory clinic 41 1.4 35 2.6 76 1.8 0.53 (0.30, 0.93) 0.03 0.75 (0.37, 1.53) 0.43
Geographic location of clinic:             
   Urban 2,476 83.5 1,169 85.8 3,645 84.2 Ref. Ref. Ref. Ref. Ref. Ref.
   Rural 491 16.6 194 14.2 685 15.8 1.20 (0.99, 1.46) 0.07 1.19 (0.98, 1.45) 0.08
Physician familiarity with the patient (patient treated by the study physician in the previous year):             
   No 1,199 40.4 475 34.9 1,674 38.7 Ref. Ref. Ref. Ref. Ref. Ref.
   Yes 1,768 59.6 888 65.1 2,656 61.3 0.79 (0.69, 0.91) < 0.001 0.95 (0.82, 1.11) 0.53
Day of the week:             
   Weekday 2,797 94.3 1,308 96.0 4,105 94.8 Ref. Ref. Ref. Ref. Ref. Ref.
   Weekend 170 5.7 55 4.0 225 5.2 1.42 (1.03, 1.95) 0.03 1.28 (0.92, 1.77) 0.15
Season:             
   Winter (12/22-03/20) 737 24.8 339 24.9 1,076 24.9 Ref. Ref. Ref. Ref. Ref. Ref.
   Spring (03/21-06/20) 855 28.8 317 23.3 1,172 27.1 1.22 (1.02, 1.47) 0.03 1.29 (1.07, 1.57) 0.01
   Summer (06/21-09/22) 645 21.7 351 25.8 996 23.0 0.84 (0.70, 1.01) 0.06 0.91 (0.75, 1.10) 0.33
   Fall (09/23-12/21) 730 24.6 356 26.1 1,086 25.1 0.94 (0.79, 1.12) 0.48 0.97 (0.81, 1.17) 0.79
  Mean SD Mean SD Mean SD       
No. visits for the same syndrome billed by the study physician in the previous 30 days (per 10 visits) 4.1 6.7 4.2 6.2 4.2 6.6 1.08 (0.95, 1.23) 0.25 1.05 (1.01, 1.08) 0.01
Physician workload: no. claims billed that day (per 10 claims) 35.1 17.4 36.5 21.0 35.5 18.6 0.96 (0.93, 1.00) 0.03 0.93 (0.90, 0.97) < 0.001
  1. 1 Multivariate analysis adjusted for all encounter characteristics in Table 3, all physician characteristics in Table 1, and all patient characteristics in Table 2.