Table 1. Univariable and multivariable Cox regression analysis of potential predictors for developing otorrhea in children with tympanostomy tubes.
| Potential predictors | ≥1 episode of TTO, n (%) | Univariable | Multivariablei | |||
| Yes (n = 616) | No (n = 568) | HR (95% CI) | HR (95% CI) | Coefficient (SE) | ||
| Age | <4 years | 305 (49.5) | 201 (35.4) | 1.00 | – | – |
| ≥4 years | 311 (50.5) | 367 (64.6) | 0.72 (0.62; 0.85) | – | – | |
| Age per year increase | – | – | 0.91 (0.87; 0.94) | 0.95 (0.91; 0.98) | −0.06 (0.02) | |
| Male gender | 360 (58.4) | 325 (57.2) | 1.08 (0.92; 1.27) | NS | NA | |
| Indication for tube placementii | Recurrent acute otitis media | 319 (51.8) | 204 (35.9) | 1.48 (1.26; 1.73) | 1.26 (1.06; 1.49) | 0.23 (0.09) |
| Chronic otitis media with effusion | 291 (47.2) | 356 (62.7) | 0.69 (0.59; 0.80) | NS | NA | |
| Previous tube placement | 228 (37.0) | 281 (49.5) | 0.83 (0.70; 0.97) | NS | NA | |
| Previous ENT surgery | Adenoidectomy | 347 (56.3) | 279 (49.1) | 1.22 (1.04; 1.44) | NS | NA |
| Tonsillectomy | 130 (21.1) | 121 (21.3) | 0.99 (0.81; 1.20) | NS | NA | |
| ≥6 URTIs in past year | 282 (45.8) | 183 (32.2) | 1.59 (1.35; 1.86) | 1.38 (1.17; 1.63) | 0.32 (0.09) | |
| Atopyiii | 199 (32.3) | 152 (26.8) | 1.12 (0.95; 1.33) | NS | NA | |
| Water exposure | 430 (69.8) | 415 (73.1) | 0.83 (0.70; 0.99) | NS | NA | |
| Attending day-care/schooliv | 282 (92.5) | 190 (94.5) | 0.79 (0.51; 1.20) | NS | NA | |
| Smoking in household | 32 (5.2) | 33 (5.8) | 0.91 (0.64; 1.30) | NS | NA | |
| Low maternal education level | 65 (10.6) | 55 (9.7) | 1.09 (0.84; 1.41) | NS | NA | |
| Overweightv | 38 (6.2) | 36 (6.3) | 0.94 (0.68; 1.31) | NS | NA | |
| ≥2 siblings | 200 (32.5) | 172 (30.3) | 1.06 (0.90; 1.26) | NS | NA | |
| Older siblings | 363 (58.9) | 285 (50.2) | 1.29 (1.10; 1.51) | 1.21 (1.03; 1.42) | 0.19 (0.08) | |
| Family history | Middle ear infections in parents | 303 (49.2) | 280 (49.3) | 1.10 (0.94; 1.29) | NS | NA |
| Middle ear infections in siblingsvi | 231 (44.0) | 241 (46.5) | 1.03 (0.86; 1.22) | NS | NA | |
| Allergy in parents | 324 (52.6) | 325 (57.2) | 0.92 (0.78; 1.07) | NS | NA | |
| Allergy in siblingsvi | 168 (32.0) | 152 (29.4) | 1.08 (0.90; 1.30) | NS | NA | |
| Gestational age <37 weeks | 75 (12.2) | 68 (12.0) | 0.99 (0.78; 1.26) | NS | NA | |
| Birth weight <2500 grams | 44 (7.1) | 41 (7.2) | 1.09 (0.80; 1.48) | NS | NA | |
| Breastfed for >3 months | 305 (49.5) | 277 (48.8) | 0.97 (0.83; 1.13) | NS | NA | |
| Pacifier use in previous year | 133 (21.6) | 79 (13.9) | 1.43 (1.18; 1.73) | NS | NA | |
| PCV7-vaccination | 339 (55.0) | 251 (44.2) | 1.42 (1.21; 1.67) | NS | NA | |
TTO = tympanostomy tube otorrhea; n = number; HR = hazard ratio; CI = confidence interval; SE = standard error; i = only results presented for independent predictors with p<0.05; NS = not significant; NA = not applicable; ii = 14 children for other indications; ENT = ear, nose and throat; URTI = upper respiratory tract infection; iii = diagnosis of allergic rhinitis, asthma, eczema or food allergy; iv = univariable analysis only including children younger than 4 years, school is mandatory for children 4 years and over; v = BMI was categorized into underweight or normal weight versus overweight according to the World Health Organization standards, corrected for age and gender. [24], [25]; vi = univariable analysis only including 1045 children with siblings; PCV-7 = 7-valent pneumococcal vaccine.