Table 1.

Positive predictive values for the coding of herpes simplex encephalitis in the DNPR

ICD-10 diagnosis category	Positive, na	Cases, n	Confirmed, n	Probable, n	PPV (95% CI)
B00.4 “Herpesviral (herpes simplex) encephalitis”	332	188	168	20	56.6 (51.1–62.0)
B00.4A “Herpesviral (herpes simplex) meningoencephalitis”	37	21	16	5	56.8 (39.5–72.9)
G05.1E “Herpesviral encephalitis”	29	22	18	4	75.8 (56.5–89.7)
Combined (B00.4, B00.4A, G05.1E)
Total	398	231	202	29	58.0 (53.0–62.9)
Period
2004–2007	137	77	70	7	56.2 (47.5–64.7)
2008–2011	170	92	79	13	54.1 (46.3–61.8)
2012–2014	91	62	53	9	68.1 (57.5–77.5)
Department type
ID or N	252	167	147	20	66.3 (60.1–72.1)
Other	146	64	55	9	43.8 (35.6–52.3)
Type of diagnosis
Primary	352	208	186	22	59.1 (53.8–64.3)
Secondary	46	23	16	7	50.0 (34.9–65.1)

Note:

^aDoes not include the 24 patients whose medical records were not retrievable for validation.

Abbreviations: DNPR, Danish National Patient Registry; ICD-10, International Classification of Diseases, tenth revision; PPV, positive predictive value; CI, confidence interval; ID, infectious diseases; N, neurology.