For the purpose of quality assurance, the Swedish Association for Otorhinolaryngology and Head and Neck surgery has developed several national registers concerning ear, nose and throat care. One of these is the National Tonsil Surgery Registry in Sweden (NTSRS). In NTSRS patients undergoing tonsil surgery for benign indications are included. Data regarding indication, surgical methods and techniques as well as patient reported outcomes measures are collected. The register is designed to facilitate description of clinical activities in a unit and help identify the need of clinical improvement programs. By compiling national data, the register can be used to describe clinical practice in a large national cohort.

The National Tonsil Surgery Register in Sweden (NTSRS), started in 1997 as one among several registers, aimed to reinforce quality in the Swedish health care and were revised 2009. Data in the NTSRS are collected through four questionnaires; two are filled in by the ENT-surgeon and two postoperative forms, filled in by the patient or the legal guardian, collecting patient related outcome measures (PROM) 30 respective 180 days after surgery.

In the first surgeon questionnaire age, sex, social security number and indication for surgery (upper airway obstruction, recurrent tonsillitis, chronic tonsillitis, peritonsillar abscess, and systemic complications because of tonsillitis or other) are recorded. This is filled in when surgery is notified.

The second surgeon questionnaire records surgical method (TE, TEA, TT or TTA), surgical instruments used for dissection (cold steel, radiofrequency, diathermy scissors, ultracision or other) and hemostasis method used (injection with epinephrine, unipolar diathermy, bipolar diathermy, ties, suture ligature, radiofrequency, other or "none other than compression with packs"). The questionnaire also records information regarding daycare/inpatient procedure and primary postoperative bleeding. Due to the configuration of the questionnaires and the ambition to cover both inpatient and daycare procedures, primary bleeding is defined as bleeding during hospitalization.

The first patient/caregiver form contains several questions mainly regarding postoperative complications. Any contact with healthcare provider due to postoperative bleeding/pain/infection as well as consequences of the contact; prescribed antibiotics and readmission/return to theatre are reported. Conformity between preoperative information and actual patient experience was is also included in this form.

The final questionnaire that is sent to the second patient/caregiver questionnaire asks for perceived symptom relief after 180 days by choosing one alternative of four statements: My symptoms are gone / My symptoms are almost gone / My symptoms have not disappeared/ My symptoms have worsened.

In order to assess coverage for the NTSRS, data has been matched on an individual level with another national register, the National Patient Register (NPR). The NPR is managed by the National Board of Health and Welfare and registration of surgical procedures is mandatory by law for all physicians in Sweden. The coverage of NTSRS for the study period 2012-2014 was 75%, 81.4% and 80.7% respectively

Inclusion Criteria:

• All patients undergoing benign tonsil surgery in Sweden

Exclusion Criteria:

• All patients operated with an C- or D0-48 ICD 10 code, indicating not benign diagnoses

All patients undergoing benign tonsil surgery in Sweden

All registered data i available online for registrating units.