Randomized Clinical Trial for Tonsil Surgery in Adults With Obstructive Sleep Apnea and Enlarged Tonsils (TONOS)

Multicenter, National, Randomized, Patient-Blinded, Parallel Group, Non-Inferiority Trial To Compare Tonsillotomy Versus Extracapsular Tonsillectomy in Adults With Obstructive Sleep Apnea and Tonsil Hypertrophy: The TONOS Trial.

The aim is to investigate whether the tissue-preserving tonsil surgery technique is as effective as complete tonsil removal in the treatment of obstructive sleep apnea. The primary outcome measure is the change in the apnea-hypopnea index (AHI) before surgery and at 4-6, 24, and 60 months after surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Tonsil Hypertrophy; Sleep Apnea, Obstructives
• Intervention / Treatment: Procedure: Tonsillectomy; Procedure: Tonsillotomy

Detailed Description

Adult reviews suggest tonsillotomy (TT) reduces morbidity compared to tonsillectomy (TE). In pediatric populations, the effectiveness of partial tonsil surgery for sleep apnea (OSA) is well-documented. It remains unclear if TT is non-inferior to TE in adults in the treatment of OSA. This study compares TE with TT in adults using change in apnea-hypopnea index as the primary endpoint.

The hypothesis is that TT is non-inferior compared to TE in treating patients with moderate or severe OSA and grade 2 to 4 tonsil size.

Participants are blinded to the allocated intervention with an allocation ratio 1:1. Participants will be recruited from patients referred to an outpatient hospital clinic. The trial will be carried out in four tertiary hospitals in Finland.

• Study Type: Interventional
• Enrollment (Estimated): 132
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jaakko M Piitulainen, MD, PhD; Phone Number: +35823130000; Email: jaakko.piitulainen@utu.fi
• Study Contact Backup: Name: Henrik Sjöblom, MD; Phone Number: +35823130000; Email: henrik.sjoblom@varha.fi

Study Locations

• Finland
  • Helsinki, Finland
    • Helsinki University Hospital
    • Contact: Johanna Ruohoalho, MD, PhD; Phone Number: +35894711; Email: firstname.lastname@hus.fi
    • Contact: Vanhapiha Nelli, MD
  • Oulu, Finland
    • Oulu University Hospital
    • Contact: Aleksi Laajala, MD; Phone Number: +35886699500; Email: firstname.lastname@oulu.fi
    • Contact: Alakärppä Antti, MD, PhD
  • Tampere, Finland
    • Tampere University Hospital
    • Contact: Saara Markkanen, MD, PhD; Phone Number: +3583311611; Email: firstname.lastname@pirha.fi
    • Contact: Saara Lesonen, MD
  • Turku, Finland
    • Turku University Hospital
    • Contact: Henrik M Sjöblom, MD; Phone Number: +35823130000; Email: hmsjob@utu.fi
    • Contact: Jenny Knubb, MD; Phone Number: +35823130000

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• BMI < 35
• Tonsil size 2 - 4
• Otherwise healthy patient fit for tonsil surgery
• Apnea-hypopnea index > 15
• Obstructive sleep apnea symptoms

Exclusion Criteria:

• Pathological hemostasis or use of anticoagulation
• Craniofacial deformities
• Neurological condition with muscular hypotonia
• Other surgical treatment for OSA

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Tonsillectomy; TE will be performed by dissection in the peritonsillar plane. Parts of the upper and lateral palatal mucosal arches will be incised, and an extracapsular dissection for complete tonsil excision will be performed. The surgical instrumentation (eg. cold steel, monopolar diathermy with a pen electrode, bipolar scissors, coblation technique or a microdebrider) is selected by the surgeon.	Procedure: Tonsillectomy; TE will be performed by dissection in the peritonsillar plane. Parts of the upper and lateral palatal mucosal arches will be incised, and an extracapsular dissection for complete tonsil excision will be performed.
Active Comparator: Tonsillotomy; TT will be performed by removing approximately 60 - 90% of the tonsillar tissue, leaving a rim of tonsillar tissue on the tonsillar fossae. The tonsil capsule will not be breached. The surgical instrumentation (eg. cold steel, monopolar diathermy with a pen electrode, bipolar scissors, coblation technique or a microdebrider) is selected by the surgeon.	Procedure: Tonsillotomy; TT will be performed by removing approximately 60 - 90% of the tonsillar tissue, leaving a rim of tonsillar tissue on the tonsillar fossae. The tonsil capsule will not be breached.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in AHI at baseline and after surgery	The primary outcome is changes in AHI measured with home sleep study	baseline, 4-6, 24 and 60 months after surgery.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Daytime sleepiness	Measured with Epworth Sleepiness Scale (ESS) questionnaire (patient-reported). Points 0-18, higher is worse.	Baseline and 6, 12, 24 and 60 months after surgery
Changes in insomnia symptoms	Measured with Insomnia Severity Index (ISI) questionnaire, points range 0-28, higher is worse.	Baseline and 6, 12, 24 and 60 months after surgery
Surgical success rate	Defined according to Sher's criteria: a reduction in AHI of >50% and a total AHI of <20 after surgery	Baseline and 6, 12, 24 and 60 months after surgery
Surgical cure rate	Defined as a total AHI of <5 after surgery	Baseline and 6, 12, 24 and 60 months after surgery
Changes in nocturnal desaturation	Changes in nocturnal desaturation measured with oxygen saturation (SaO2) mean, min, and SpO2 <90% (T90) and ODI3, measured with home sleep study	Before surgery and 4-6, 24 and 60 months after surgery

Collaborators and Investigators

• Sponsor: Turku University Hospital
• Collaborators: Helsinki University Central Hospital; Oulu University Hospital; Tampere University Hospital
• Investigators: Study Director: Jaakko M Piitulainen, MD, PhD, Turku University Hospital; Principal Investigator: Henrik Sjöblom, MD, Turku University Hospital; Principal Investigator: Jenny Knubb, MD, Turku University Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): October 1, 2026
• Primary Completion (Estimated): January 1, 2031
• Study Completion (Estimated): January 1, 2036

Study Registration Dates

• First Submitted: March 27, 2026
• First Submitted That Met QC Criteria: May 6, 2026
• First Posted (Actual): May 12, 2026

Study Record Updates

• Last Update Posted (Actual): June 3, 2026
• Last Update Submitted That Met QC Criteria: May 31, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: tonsillectomy; sleep apnea; adults; tonsillotomy; intracapsular tonsillectomy; tonsil hypertrophy
• Additional Relevant MeSH Terms: Nervous System Diseases; Respiratory Tract Diseases; Respiration Disorders; Sleep Wake Disorders; Apnea; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Apnea Syndromes; Surgical Procedures, Operative; Otorhinolaryngologic Surgical Procedures; Tonsillectomy
• Other Study ID Numbers: VARHA/28047/13.02.02/2025

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data dictionary describing the variables.
• IPD Sharing Time Frame: Study protocol and Statistical Analysis Plan at the Beginning will be published at Clinical Trials.gov before the enrolment has started.
• IPD Sharing Access Criteria: Open access
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No