A PRimary care trial of a website based Infection control intervention to Modify Influenza-like illness and respiratory infection Transmission

Index patients will be prompted by email to log onto the website monthly to complete questionnaires about illnesses during the last month since the duration of symptoms can be remembered reliably over a period of a few weeks. For each episode the index person will document:
1. The nature of the infection
2. The duration of symptoms rated moderately bad (which we have shown is the most likely to be sensitive to change for individuals with cough and fever and can be remembered reliably over a period of a few weeks)
3. The number of days where work/normal activities were impaired
4. Whether other family members either had a similar infection before or after the index case, and what the time interval was
5. Whether contact with the health service was needed
6. How well the index patient and other family members complied with the target behaviours (for the intervention group only)

The monthly illness information will be supplemented by a questionnaire at the end of the winter documenting the summary information, and which can be validated against the monthly information. We will base our definition of RTI on consensus definitions developed in previous studies - which have defined a respiratory tract infection as 2 symptoms of an RTI for at least 1 day or 1 symptom for 2 consecutive days. Evidence of transmission will be defined as a respiratory illness developing within a week of another family member.

At the end of the study all patients' GP notes will be reviewed to document admission to hospital for respiratory or cardiovascular complications, whether patients attended the GP for their ILI or other respiratory tract infections68, whether antibiotics or antivirals were prescribed, and/or any subsequent referrals. Assessment of the notes will be made blind to group, and has been shown to be reliable and unbiased. We will assess attitudes, beliefs, intentions, and self-reported adherence for each behaviour on 7 point Likert scales both in the pilot study (after 1 month and 3 months), and in the main trial at the end of the winter (we will randomly choose 1:20 patients for this outcome). These outcomes will be measured in both groups in the main trial only at the end of the winter, to minimise any effect on behaviour change of administering questionnaires in the control group. These outcomes will allow us to check whether the intervention is successful in effecting change and whether outcomes of the intervention are mediated by changes in these variables.To accompany the winter illness questionnaire we will use an adherence questionnaire (the 'Problematic Experiences of Therapy Scale'; PETS) that we have used in previous studies, including the MRC ATEAM trial, and two vertigo trials To reduce social desirability effects on reporting of adherence, the PETS asks patients to what extent they have been prevented from carrying out the intervention by socially acceptable reasons (e.g. symptoms too severe or aggravated by the intervention; doubts about efficacy; uncertainty about how to carry out the intervention; practical problems such as lack of time or opportunity, forgetting). They are only then asked how often and over how many weeks/months they adhered to each aspect of the intervention. To compare the effects of the intervention as a whole with the effects of the website and the target behaviours, in addition to the main intention-to-treat analysis we will carry out per protocol analyses to determine the effectiveness of the intervention in a) those who logged on to the website and b) those who reported adhering to each of the different target behaviours.