An attempt at an epidemiological explanation - Epib.nl

Chapter 5distribution of the clinical presentation among the various serogroups (X' = 22.8; 6df: P < .001).No significant association was found between the CFR and serotype or sub type (X'= 3.1; 5 df: P = .680 and X' = 13.1; 8 df: P = .109, respectively; Table 2). Theserotypes 2a and 2b and the subtypes P1.2, P1.5, P1.5,2, P1.15 and P1.16 tended tohave somewhat higher CFRs. Lower CFRs were found in patients with disease due toserotype 4 (5.4%) and subtype P1.4 (3.5%), which are at present the most prevalentserotype and subtype in the Netherlands.The association between the CFR and LOS immunotype for each serogroup isshown in Table 3. Immunotypes L2 and L4 were associated with the highest CFR(11 .3%), but this association was not statistically significant (X' = 3.7; 3 df: P = .296).Within serogroup E, the CFR in disease due to L2 and L4 (8.5%) was almost twiceas high as that in disease due to the L3 group of immunotypes (4.8%), but amongserogroup C isolates these CFRs were almost equal (12.8% and 14.0%, respectively).Table 3. Distribution of cases and case-fatality rates (between brackets) of meningococcal disease inthe Netherlands, 1989-1990, by immUDotypC and serogroupSerogroupImmuDotypccategory A B C Other TotalLl/8 0 69 (5.8) 5 (.0) 1 (.0) 75 (5.3)1214 0 59 (8.5) 47 (12.8) 9 (22.2) 115 (11.3)L3/1/8 8 (25 .0) 289 (4.8) 50 (14.0) 8 (25 .0) 355 (7.0)Other 5 (.0) 0 3 (.0) 1 (.0) 9 (.0)Total 13 (15.4) 417 (5.5) 105 (12.4) 19 (21.1) 554 (7.6)NOTE:In 8 cases due to serogrollp B no immunolype could be assignedTable 4 shows the age-specific CFRs, according to gender. The highest CFR isfound among patients over 50 years of age (29.7%), followed by infants aged 0-5months (16.7%) and teenagers (10.3%; X' = 38.3; 4 df: P < .001). The CFR amongfemale patients (11.2%) differed significantly from the CFR among males (4.4%; X' =9.3; 1 df: P = .002). Female patients were older on the average (X' = 7.9; 4 df: P =.094). The largest gender-specific CFR differences were found in the age-categories10-19 and ;,;50 years of age, in which females outnumbered males (Table 4). Therewas no significant association between gender and serogroup (X' = .1; 3 df: P = .996)or clinical presentation (X' = .0; 2 df: P = .993).There were 26 patients (4.8%) with a predisposing factor. The CFR among thosepatients (19.2%) was almost 3 times higher than that of patients without a predisposingfactor (6.7%; Fisher's exact test: P = .034). Predisposed patients were found tosuffer more often from septicemia than other patients (X' = 11.2; 2 df: P = .004).68