To 1984.

Study characteristics
Methods	2‐arm RCT with at least 12 months follow‐up (mean follow‐up of 2 years (range 1 to 5 years)) Randomised by ear
Participants	Location: UK Setting of recruitment and treatment: no details given Study dates: March 1976 to June 1982 Sample size: 54 children Number randomised: 54 ears in intervention group, 54 ears in comparison group Number completed: 54 ears in intervention group, 54 ears in comparison group Participant (baseline) characteristics: Age (mean): 7 years and 6 months (range 47 months to 14 years) Gender: males 29/54 (54%), females 25/54 (46%) Duration of disease: not reported but mean follow‐up before operation 7.2 months Treatment used before trial entry: unspecified "medical measures" Inclusion criteria: Children under the age of 14 years Presented with secretory otitis media that failed to respond to "medical measures" Reviewed to confirm the "chronic nature of the condition as shown both clinically and by persistently abnormal audiograms and tympanograms" Exclusion criteria: Children with asymmetrical hearing loss, in whom the mean hearing levels on the 2 sides showed a difference of more than 6 dB Children who had grommets inserted for established complications of the disease, such as retraction pockets and obvious thinning of the drum
Interventions	Ventilation tube: insertion of a Shepherd grommet; 22 in the better ear* (9 right and 13 left), 25 in the worse ear* (11 right and 14 left), 7 in which both ears were equal (2 right and 5 left) (*where these refer to comparisons of audiograms) Myringotomy: "most participants" had myringotomy in the contralateral ear Use of additional interventions: all participants received adenoidectomy if adenoids had not previously been removed (n = 9), and were present (n = 1 no adenoids)
Outcomes	Primary outcome: hearing level Secondary outcomes: adverse events: perforation, retraction segments, tympanosclerosis
Funding sources	Not reported
Declarations of interest	No declarations are made
Notes	Research integrity checklist: No retraction notices identified Prospective registration not applicable (published before 2010) Baseline characteristics are not relevant (split‐body trial) No loss to follow‐up was reported No implausible results The number randomised to each group was identical as this was a split‐body trial
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“Those who did not respond were submitted to the removal of adenoids (if present) and the insertion of a Shepard grommet in one ear chosen at random.” No information is provided about the process used for randomly selecting an ear.
Allocation concealment (selection bias)	Unclear risk	"Those who did not respond were submitted to the removal of adenoids (if present) and the insertion of a Shepard grommet in one ear chosen at random." No information is provided about concealment of allocation.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Surgeons could not be blinded. There is a strong possibility that personnel could identify which treatment a participant received and hence change their behaviour as a result.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	“The patients were under the care of 2 consultants working independently and the results were reviewed by an independent observer.” It is unclear if this means that the observer was blinded to group allocation, or was simply a separate assessor.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Follow‐up appears to be 100% at 12 months for hearing threshold data. Adverse events are reported at later follow‐up times but no information is provided on how many had dropped out. It appears that the number of dropouts after 1 year could have been many: "Twenty‐three children have been discharged from follow‐up having been well and with normal ears for about a year; some of them have had further surgical treatment on one or both sides. The mean follow‐up for this group is 27 months." For adverse event outcomes, the risk of bias for this domain is high.
Selective reporting (reporting bias)	Unclear risk	No protocol or trial registration was found. The published paper reports all expected outcomes.
Other bias	High risk	“In the other ear, myringotomy was usually performed; those cases in the present trial in which myringotomy was not performed were not considered to introduce a significant variation, as Bennett & Chakraborty showed that myringotomy did not produce a more beneficial effect than adenoidectomy alone.” As the contralateral ear was sometimes treated with myringotomy, and sometimes not, it is unclear whether the study really compared a VT to no treatment, or to myringotomy.