Table 3. Trend statistics and significance values of genotyping parameters related to invasive meningococcal disease (IMD)-associated isolates recovered in Republic of Ireland over a 19 epidemiological year (EY) period, EY1996/1997 to EY2014/2015.
Data were analysed for trend using the non-parametric Kendall’s rank correlation coefficient test (Stata, version 14; StataCorp LP, College Station, Texas, USA).
| Genotyping Parameter (n = 1121) | Descriptive statistics for 19 EYs | KS* | p-value | |||
|---|---|---|---|---|---|---|
| range | median | 95% CI | overall | |||
| % of all cases genotyped (overall 1121/3637) | 17.5–49.25 | 33.11 | 28.99–35.81 | 30.82% | 53 | 0.0689 |
| Representativeness at serogroup level of isolate population genotyped each EY to proportion of cases associated with each serogroup each EY, expressed as a ratio | ||||||
| menB isolates genotyped:menB IMD cases (overall 854/1121:2866/3637 = 0.967:1) | 0.81–1.05 | 0.966 | 0.93–1 | 0.967 | -7 | 0.8337 |
| menC isolates genotyped:menC IMD cases (overall 211/1121 vs. 627/3637) | 0–3.6 | 1.20 | 0.99–2.46 | 1.09 | 10 | 0.7527 |
| menW isolates genotyped:menW IMD cases (overall 28/1121 vs. 45/3637) | 0–4.19 | 1.80 | 0–2.41 | 2.02 | -22 | 0.4546 |
| menY isolates genotyped:menY IMD cases (overall 25/1121 vs. 37/3637) | 0–3.45 | 1.67 | 0–2.79 | 2.19 | -6 | 0.8587 |
| Proportion (%) of isolates assigned to specific STcc each EY | ||||||
| all isolates—cc8 | 0–16.67 | 0.00 | 0–2.34 | 2.60% | -68 | 0.0064 |
| all isolates—cc11 | 0–42.86 | 6.25 | 4–22.66 | 16.70% | -65 | 0.0252 |
| all isolates—cc22 | 0–6.25 | 3.20 | 0–3.92 | 2.90% | -7 | 0.8307 |
| all isolates—cc23 | 0–3.13 | 0.00 | 0–1.32 | 0.54% | 27 | 0.2669 |
| all isolates—cc162 | 0–13.79 | 0.00 | 0–1.32 | 1.10% | 40 | 0.0761 |
| all isolates—cc213 | 0.96–11.29 | 3.85 | 1.96–6.25 | 3.80% | 66 | 0.0229 |
| all isolates—cc269 | 2.38–37.25 | 17.31 | 12.26–25 | 16.90% | 55 | 0.0589 |
| all isolates—cc461 | 0–11.76 | 0.00 | 0–3.57 | 1.60% | 47 | 0.0801 |
| all isolates—cc41/44 | 20.59–51.92 | 39.47 | 31.37–45.16 | 38.50% | 11 | 0.7264 |
| all isolates—assigned STcc- richness (no of STcc) | 6–13 | 10.00 | 10–11 | 19 | -27 | 0.3485 |
| all isolates–assigned STcc- Gini-Simpson index (Ds) | 0.7–0.86 | 0.77 | 0.73–0.82 | 0.79 | 53 | 0.0689 |
| all isolates—assigned STcc- Shannon entropy (H') | 1.37–2.04 | 1.75 | 1.67–1.97 | 2.01 | 45 | 0.1237 |
| all isolates—assigned STcc- Pielou's Evenness (Eh) | 0.64–0.87 | 0.74 | 0.73–0.81 | 0.65 | 89 | 0.0021 |
| all isolates—assigned STcc- Clonal diversity (CD) index | 0.09–0.5 | 0.20 | 0.13–0.28 | 0.02 | 116 | 0.0001 |
| Proportion (%) of menB isolates assigned to specific STcc each EY | ||||||
| menB—cc32 | 0–13.89 | 5.88 | 4.17–9.46 | 7.50% | -62 | 0.0327 |
| menB—cc162 | 0–15.38 | 0.00 | 0–1.56 | 1.40% | 40 | 0.0761 |
| menB—cc 213 | 1.89–12.07 | 5.13 | 2.78–7.69 | 5% | 53 | 0.0685 |
| menB—cc 269 | 5–39.58 | 19.15 | 17.57–26.56 | 22% | 57 | 0.0501 |
| menB—cc 461 | 0–18.18 | 0.00 | 0–3.77 | 2.10% | 48 | 0.0740 |
| menB—cc 41/44 | 31.82–63.51 | 50.00 | 40.74–55.06 | 50.20% | -79 | 0.0064 |
| menB—assigned STcc—richness (no of STcc) | 3–12 | 8.00 | 7–10 | 18 | 3 | 0.9431 |
| menB—assigned STcc–Gini-Simpson index (Ds) | 0.56–0.85 | 0.7 | 0.63–0.75 | 0.69 | 77 | 0.0078 |
| menB—assigned STcc—Shannon entropy (H') | 0.93–1.84 | 1.49 | 1.35–1.69 | 1.66 | 59 | 0.0424 |
| menB—assigned STcc—Pielou's Evenness (Eh) | 0.59–0.89 | 0.71 | 0.68–0.78 | 0.57 | 83 | 0.0041 |
| menB—assigned STcc—Clonal diversity (CD) index | 0.07–0.44 | 0.23 | 0.14–0.28 | 0.02 | 91 | 0.0016 |
*KS–Kendall’s Score; CI, Confidence interval; IMD, invasive meningococcal disease; menB, meningococcal serogroup B; menC, meningococcal serogroup C; menW, meningococcal serogroup W; menY, meningococcal serogroup Y; STcc, sequence type clonal complex (cc).
P value of <0.05 (highlighted in bold text) denotes a significant trend over the 19EY period the direction and extent of which can be inferred by the positive (increasing) or negative (decreasing) Kendall’s score value.