Randomised controlled trial of rhinothermy for treatment of the common cold: a feasibility study

van de Hei, Susanne; McKinstry, Steven; Bardsley, George; Weatherall, Mark; Beasley, Richard; Fingleton, James

Participants in this study were recruited primarily through social media so the results should be 388 generalisable to people in the community with symptoms of the common cold. 389 390 Three main limitations apply to these results. Firstly, this study was designed as a feasibility 391 study which means that although the modified Jackson score was a pre-specified efficacy 392 outcome measure, we did not formally specify it as the primary outcome measure. Secondly, due 393 to the nature of the intervention we were unable to blind participants and investigators to the 394 allocated intervention and a future study aiming to replicate these results should explore the 395 option of sham rhinothermy. Finally, the small sample size means that although this study 396 showed clinically and statistically significant results it can be considered relatively 'fragile', in that 397 the modified Jackson score would only need to change in a small number of participants who 398 received the rhinothermy intervention to match the control group for our conclusions to be 399 different. [33, 34] A formal fragility index cannot be calculated for the change in modified Jackson 400 score as it is not a dichotomous variable. The complete follow-up of all participants helps protect 401 against this fragility, however due to the above limitations a larger replication study is required. 402 participants used the myAIRVO 2 device for two hours per day on average throughout the 5 day 419 treatment period, and for 2.6 hours on the days of use. As instructed not all participants used the 420 device late in the treatment course once their symptoms had improved. Around a third of 421 participants reduced the flow rate to 25 or 30L/min suggesting that giving participants the option 422 of reducing the flow from the initial 35L/min, or having a lower starting flow is worthwhile. The 423 difference between the randomised groups was observed within 24 hours, so that the efficacy of 424 single dose regimens or sessions over a two to three day period, which may enhance its 425 implementation in clinical practice, will be worth further study. However, while alternative 426 rhinothermy regimens will need to be assessed, our study findings suggest that the regimen used 427 in this feasibility study should also be used in future RCTs. 428