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Volume 19, Number 9—September 2013

Research

New Estimates of Incidence of Encephalitis in England

Julia Granerod1Comments to Author , Simon Cousens, Nicholas W.S. Davies1, Natasha S. Crowcroft1, and Sara L. Thomas
Author affiliations: Public Health England, London, UK (J. Granerod); London School of Hygiene and Tropical Medicine, London (S. Cousens, S.L. Thomas); Chelsea and Westminster Hospital, London (N.W.S. Davies); Public Health Ontario, Toronto, Ontario, Canada (N.S. Crowcroft)

Main Article

Table 4

Sensitivity analysis adjusting for variation in positive predictive value for HES-only admissions*

Positive predictive value, % HES only PHE study only Both sources Estimated total no. cases (95% CI) % Completeness (95% CI)
Estimated incidence
HES† PHE study
Encephalitis-specific code in any of the 20 diagnostic fields
30 114 54 59 332 (272–391) 52 (43–61) 34 (27–41) 3.42
40 152 54 59 405 (332–477) 52 (43–61) 28 (22–34) 4.17
50 190 54 59 477 (392–562) 52 (43–61) 24 (18–29) 4.91
54 206 54 59 508 (418–598) 52 (43–61) 22 (17–27) 5.23
60 228 54 59 550 (452–648) 52 (43–61) 21 (16–25) 5.67
70 266 54 59 623 (512–734) 52 (43–61) 18 (14–22) 6.42
80
304
54
59
696 (572–819)
52 (43–61)
16 (12–20)
7.17
Encephalitis-specific code in primary field only
30 71 60 53 265 (214–315) 47 (38–56) 43 (34–51) 2.73
40 94 60 53 314 (254–374) 47 (38–56) 36 (28–44) 3.23
50 117 60 53 363 (293–433) 47 (38–56) 31 (24–38) 3.74
54 127 60 53 384 (310–458) 47 (38–56) 29 (23–36) 3.96
60 141 60 53 414 (334–494) 47 (38–56) 27 (21–34) 4.26
70 164 60 53 463 (374–553) 47 (38–56) 24 (19–30) 4.77
80 188 60 53 514 (415–614) 47 (38–56) 22 (17–27) 5.29

*Incidence = cases/100,000 population. HES, Hospital Episode Statistics; PHE, Public Health England
†Due to the Lincoln-Petersen formula, if the number of HES-only admissions varies, the total HES admissions (HES only plus matched) is proportional to the estimated total number of cases; hence, the completeness of HES (ratio) does not change with varying positive predictive value.

Main Article

1On behalf of the United Kingdom Public Health England Aetiology of Encephalitis Study Group (members listed at the end of this article).

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