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Evidence summaries

Probiotics for Preventing Acute Otitis Media in Children

Probiotics may prevent acute otitis media (AOM) in children not prone to AOM. Level of evidence: "C"

The quality of evidence is downgraded by study limitations (unclear allocation concealment), and by inconsistency (unexplained variability in results).

Summary

A Cochrane review [Abstract] 1 included 17 studies with a total of 3 488 children (mean age 2.4 years). Twelve studies included children who were not prone to acute otitis media (AOM), and 5 studies included children prone to AOM. The definition of 'otitis-prone' was not clear and may have involved a subjective element. Probiotic strains varied: 11 studies evaluated Lactobacillus-containing probiotics, and 6 evaluated Streptococcus-containing probiotics. Also probiotic dose, frequency, and duration of administration varied considerably across studies (duration of administration ranged from 20 days to 2 years).

Probiotics decreased the proportion of children experiencing 1 or more episodes of acute otitis media (AOM) during the treatment (NNTB=10).Post hoc subgroup analysis found that this effect was evident only in children who were not otitis-prone (NNTB=9); the effect was not observed for otitis-prone children (test for subgroup differences was significant, p=0.007). Probiotics decreased the proportion of children having other infections (NNTB=12) and the proportion of children taking antibiotics for any infection (NNTB=8; table T1). There was no difference in the mean number of school days lost (MD 0.95, 95% CI 2.47 to 0.57, statistical heterogeneity I2 =54%; 5 studies, n=1 280). There were no differences in adverse events between probiotic and comparator groups.

Probiotic compared to placebo

OutcomeRelative effect (95% CI)Risk with placeboRisk with probiotic (95% CI)Participants (studies)
Proportion of children with AOM (overall)RR 0.77(0.63 to 0.93), I2 = 72%390 per 1000300 per 1000(246 to 362)2 961(16)
  • Proportion of children with AOM (children not prone to AOM)
RR 0.64(0.49 to 0.84), I2 = 59%295 per 1000189 per 1000(145 to 248)2 227(11)
  • Proportion of children with AOM (children prone to AOM)
RR 0.97(0.85 to 1.11)660 per1000641 per 1000(561 to 733)734(5)
Difference in proportion of children with other infectionsRR 0.75(0.65 to 0.87), I2 = 64%363 per 1000272 per 1000(236 to 316)3 610(11)
Difference in the use of antibioticsRR 0.66(0.51 to 0.86), I2 = 70%397 per 1000262 per 1000(203 to 342)1 768(8)
Adverse eventsOR 1.54(0.60 to 3.94), I2 =56%186 per 1000260 per 1000(121 to 474)395(4)
Clinical comments

The clinical significance of the observed positive effect is reduced by the unexpected finding that probiotics prevent AOM only in children who were not otitis-prone, and the effect was not observed for otitis-prone children. In addition, there are uncertainties about the optimal strain, as well as the duration, frequency, and timing of probiotics administration.

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