years. Severely affected children who undergo surgery on average have one fewer sore throat per year in the subsequent one or two years, compared to those who do not. Specifically one review of five randomized controlled trials, found a decrease from 3.6 to 3.0 episodes in the year following surgery. In less severely affected children, surgery results in an increase, rather than a decrease of sore throats when the sore throat directly following surgery is included. Surgery results in a reduction in school absence in the year after surgery, but the strength of evidence is low. Surgery does not result in an improvement in the quality of life. Benefits of surgery do not persist over time. Those with frequent throat infections often spontaneously improve over a year without surgery. Therefore, a certain number of people who undergo surgery will do so unnecessarily as they would not have had further episodes of tonsillitis had they not had surgery. Evidence in adults is unclear. In 2019, the American Academy of Otolaryngology & Head and Neck Surgery (AAO-HNS) recommended:Many cases of the sore throat have other causes than tonsillitis and tonsillectomy is therefore not indicated for those cases. The diagnosis of tonsillitis is often made without testing for bacteria. The UK National Health Service states that it is very rare that someone needs to have their tonsils taken out, and it is usually only necessary in case of severe tonsillitis that keeps recurring. Obstructive sleep apnea Tonsillectomy improves obstructive sleep apnea (OSA) in most children. A 2015 Cochrane review found moderate quality evidence for benefits in terms of quality of life and symptoms but no benefit in attention or academic performance. It recommended that physicians and parents should weigh the benefits and risks of surgery as OSA symptoms may spontaneously resolve over time. An AHRQ review however did find improvements at school. The procedure is recommended for those who have OSA that has been verified by a sleep study. Studies have shown that treatment success of uvulopalatopharyngoplasty with tonsillectomy increases with tonsil size. Other There is no good evidence for other uses such as tonsil stones, bad breath, trouble swallowing, and an abnormal voice in children. Complications While generally safe, tonsillectomy may result in several complications, some of which are serious. Complications are divided into primary (first 24 hours after surgery), and secondary (after 24 hours), with bleeding being the most common complication.