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Table 4 Univariate and multivariate analysis of factors associated with sputum S. pneumoniae and S. aureus colonisation

From: Prevalence and antimicrobial resistance profiles of respiratory microbial flora in African children with HIV-associated chronic lung disease

Variable No. observations (n = 400) § Streptococcus pneumoniae Staphylococcus aureus
No. isolates (n = 100)φ OR [95% CI] p Adjusted OR [95% CI] p No. isolates (n = 114)λ OR [95% CI] p Adjusted OR [95% CI] p
Group
 CLD- 18% (74) 17% (17) Reference   Reference   18% (21) Reference   Reference  
 CLD+ 82% (326) 83% (83) 1.2 [0.6–2.1] 0.66 1.3 [0.6–2.6] 0.52 82% (93) 1.0 [0.6–1.8] 0.98 1.0 [0.5–1.8] 0.92
Study site
 Malawi 27% (108) 13% (13) Reference   Reference   18% (21) Reference   Reference  
 Zimbabwe 73% (292) 87% (87) 3.1 [1.7–6.1] <0.001 3.1 [1.4–7.3] 0.01 82% (93) 1.9 [1.2–3.4] 0.02 2.1 [1.1–4.2] 0.04
Sex
 Female 52% (207) 52% (52) Reference   Reference   50% (57) Reference   Reference  
 Male 48% (193) 48% (48) 1 [0.6–1.6] 0.95 0.9 [0.6–1.5] 0.73 50% (57) 1.1 [0.7–1.7] 0.66 1.1 [0.7–1.8] 0.57
Season of sample collection
 Dec–Apr - Rainy 36% (143) 26% (26) Reference   Reference   32% (37) Reference   Reference  
 May–Aug - Cool 39% (157) 41% (41) 1.6 [0.9–2.8] 0.03 1.6 [0.9–3.0] 0.04 37% (42) 1.1 [0.6–1.8] 0.25 1.1 [0.6–1.8] 0.27
 Sep–Nov - Hot 25% (100) 33% (33) 2.2 [1.2–4.1] 2.3 [1.2–4.4] 31% (35) 1.5 [0.9–2.7] 1.6 [0.9–2.8]
Enrolment age category
 17-19y 33% (130) 38% (38) Reference   Reference   39% (45) Reference   Reference  
 13-16y 40% (161) 39% (39) 0.8 [0.5–1.3] 0.34 0.8 [0.5–1.4] 0.38 38% (43) 0.7 [0.4–1.1] 0.15 0.7 [0.4–1.2] 0.25
 6-12y 27% (109) 23% (23) 0.7 [0.4–1.2] 0.6 [0.3–1.2] 23% (26) 0.6 [0.3–1.0] 0.6 [0.3–1.1]
Number of years on ART
 6 m- < 2y 9% (35) 12% (12) Reference   Reference   9% (10) Reference   Reference  
 2- < 4y 18% (71) 21% (21) 0.8 [0.3–1.9] 0.39 0.6 [0.2–1.5] 0.04 17% (19) 0.9 [0.4–2.3] 0.83 0.7 [0.3–1.8] 0.57
 4y- < 6y 20% (79) 19% (19) 0.6 [0.3–1.5] 0.4 [0.2–1.0] 23% (26) 1.2 [0.5–3.0] 0.9 [0.4–2.4]
 6y+ 53% (208) 47% (47) 0.6 [0.3–1.2] 0.3 [0.1–0.8] 51% (58) 1 [0.5–2.2] 0.6 [0.3–1.6]
CD4 count
  > 500 63% (251) 63% (63) Reference     59% (67) Reference    
 200–500 28% (110) 26% (26) 0.9 [0.5–1.6] 0.81    32% (36) 1.3 [0.8–2.2] 0.51   
  < 200 10% (38) 11% (11) 1.2 [0.6–2.5]    10% (11) 1.1 [0.5–2.3]   
Enrolment viral load
 Unsuppressed 42% (169) 35% (35) Reference     47% (54) Reference   Reference  
 Suppressed 58% (231) 65% (65) 1.5 [0.9–2.4] 0.09 1.4 [0.8–2.3] 0.22 53% (60) 0.8 [0.5–1.2] 0.19 0.7 [0.4–1.1] 0.09
ART regimen
 PI-based regimen - 2nd line 24% (98) 27% (27) Reference   Reference   25% (28) Reference   Reference  
 NNRTI-based regimen -1st line 76% (302) 73% (73) 0.9 [0.5–1.5] 0.57 1.1 [0.6–2.1] 0.75 75% (86) 1 [0.6–1.7] 0.947 1.2 [0.7–2.2] 0.54
Ever treated for TB
 No 74% (294) 65% (65) Reference   Reference   72% (82) Reference   Reference  
 Yes 26% (104) 35% (35) 1.8 [1.1–2.9] 0.02 1.8 [1.0–3.2] 0.04 28% (32) 1.2 [0.7–1.9] 0.58 1.0 [0.6–1.8] 0.92
Enrolment weight- for-age- z-score
 Not underweight 54% (217) 61% (61) Reference     54% (61) Reference    
 Underweight 46% (183) 39% (39) 0.7 [0.4–1.1] 0.12    46% (53) 1.0 [0.7–1.6] 0.85   
Enrolment height-for-age- z-score -
 Not stunted 55% (218) 59% (59) Reference   Reference   58% (66) Reference   Reference  
 Stunted 46% (182) 41% (41) 0.8 [0.5–1.2] 0.3 0.9 [0.5–1.5] 0.64 42% (48) 0.8 [0.5–1.3] 0.39 0.8 [0.5–1.3] 0.46
Ever repeated a grade
 No 46% (180) 49% (49) Reference     47% (54) Reference    
 Yes 54% (211) 51% (50) 0.8 [0.5–1.3] 0.43    53% (60) 0.9 [0.6–1.4] 0.74   
MRC dyspnoea score
 1 or 0 60% (240) 68% (67) Reference   Reference   65% (73) Reference   Reference  
  > 1 40% (159) 32% (32) 0.7 [0.4–1.0] 0.079 0.9 [0.5–1.7] 0.86 35% (40) 0.8 [0.5–1.2] 0.25 1.1 [0.6–2.0] 0.67
  1. § Missing values: Number of years on ART (7), CD4 count (1), Ever treated for TB (2), Ever repeated a grade (9) and MRC dyspnoea score (1). φ n = 99 for the number of years on ART, ever repeated a grade, MRC dyspnoea score. λn = 113 for the number of years on ART and MRC dyspnoea score. Variables with two levels where a level is less than 10% of total observations were not tested for associations. These included current school attendance and taking cotrimoxazole. Variables that have values in the adjusted odd ratios column were included in the multivariate model for that bacteria. Variables with p values <0.25 were included in the multivariate model except where they were colinear with another variable within the model. Weight-for-age was colinear with height-for-age and hence excluded from the model. Ever repeated a grade was excluded because of co-linearity with MRC score. CD4 count is colinear with viral load suppression. Clinically relevant variables (a priori-defined) that were included in the multivariate model regardless of significance were group, age, sex, site, season of sample collection, number of years on ART, enrolment viral load, ART regimen, ever treated for TB, enrolment height-for-age z-score and MRC dyspnoea score