Table 2.

Most important randomized controlled clinical trials analyzing the efficacy of tonsil surgery compared to a control group.

Authors	Age, years	Numbers included/screened	Eligibility	Intervention (I) Comparator (C)	Primary outcome	Quality of life measurement	Results
Paradise et al. (4)	3–15	91/2,034	•≥7 episodes in the preceding year OR •≥5 episodes in each of the 2 preceding years OR •≥3 episodes in each of the preceding 3 years	I: Tonsillectomy or adenotonsillectomy C: Medical treatment	Episodes of throat infections over 3 years		I: 4.62 infections C: 7.95 infections Tonsillectomy had better outcome
Paradise et al. (102)a	3–15	177/2,174	Aged 3–6 years: •4–6 qualifying units in the preceding year and (≥1 “counting” unit = plus other defined symptoms) OR •4 units in each of the past 2 years (≥2 “counting” unit per year = plus other defined symptoms) Aged 7–15 years: •4–6 qualifying units in the preceding year and (≥1 “counting” unit = plus other defined symptoms) OR •3 units in each of the past 2 years (≥1 “counting” unit per year = plus other defined symptoms) •In addition, if criteria were not documented, for all children, aged 7–15 years: •No Paradise criteria documentation: documentation of ≥1 unit in last 4 months, OR •In case of incomplete documentation: ≥1 unit in last 3 months.	I1: Tonsillectomy I2: Adenotonsillectomy C: Medical treatment	Episodes of throat infections over 3 years		I1: 1.55 infections I2: 1.63 infections C: 2.77 infections Tonsillectomy had better outcome, but illness rates were moderate. Adenotonsillectomy was no more efficacious than tonsillectomy alone
Paradise et al. (102)a	3–15	151/2,174	•Same as Paradise et al., see above	I: Adenotonsillectomy C: Medical treatment	Episodes of throat infections over 3 years		I: 1.74 infections C: 2.93 infections Adenotonsillectomy had better outcome, but illness rates were moderate.
van Staaij et al. (103)	2–8	300/1,226	•Adenotonsillectomy indicated according to “current medical practice” in Netherlands. ENT surgeons were asked to provide the indication they considered most important for surgery: recurrent throat infections (3 or more a year) or other indications such as obstructive problems or recurrent upper respiratory tract infections	I: Adenotonsillectomy C: Waiting	Incidence of fever (a temperature of 38.0°C or higher) for at least 1 day for 2 years		I: 5.31 fever days; 0.56 infections C: 5.93 fever days; 0.77 infections Tonsillectomy had better outcome
Alho et al. (104)	≥15	70/298	•≥3 episodes in 6 months OR •≥4 episodes in 12 months	I: Tonsillectomy C: Waiting	Proportion of patients with GAS episodes within 90 days	Glasgow Benefit Inventory	I: 1 patient with recurrent infection C: 8 patients with recurrent infection Tonsillectomy had better outcome
Lock et al. (105)	4–15	268/1,546	•≥4 episodes of sore throat within each of the preceding 2 years OR •≥6 episodes of sore throat within the last year	I: Tonsillectomy C: Medical treatment	Monthly numbers of episodes of sore throat in the 2 years	PedsQoL, parent-reported	I: 0.50 first year, 0.13 s year C: 0.64 first year, 0.33 s year Tonsillectomy had better outcome
Koskenkorva et al. (106)	≥13	86/260	•≥3 episodes in 12 months	I: Tonsillectomy C: Waiting	Proportion of patients with severe episode of pharyngitis within 5 months		I: 38% C: 41% Tonsillectomy had better outcome.
Wilson et al. (32)	≥16	453/4,165	UK guideline for tonsillectomy: •≥7 sore throats in the preceding year, OR •≥5 episodes in each of the preceding two years, OR •≥3 episodes in each of the preceding three years	I: Tonsillectomy C: Medical treatment	Number of sore throat days over 2 years	Tonsil Outcome Inventory 14	I: Median 23 days C: Median 30 days Tonsillectomy had better outcome.

^a The results of two trials were presented in one publication.