Table 1 List of potential predictors considered for the risk prediction models
Factor | Additional information |
|---|---|
Age | Age recorded at the time of consultation categorised into 11 groups: < 5 years, 5–10, 10–15, 15–20, 20–30, 30–40, 40–50, 50–60, 60–70, 70–80, 80+. The exception was for the UTI model where there were no events in the 10–15 category (merged to create a 10–20 years category). |
Gender | Male/female |
Charlson Comorbidity Index [22] | A score summarising the number and severity of comorbidities affecting the patient. The overall score ranges from 0 to 31 [23] but was categorised into five groups: • Very low—score = 0 or 1 • Low—score = 2 or 3 • Medium—score = 4 or 5 • High—score = 6 or 7 • Very High—score > 7 |
Socioeconomic status | Determined by linking the postcode of a patient’s residence to the Index of Multiple Deprivation 2010 classification [24]. IMD was categorised into quintiles: IMD 1 (least deprived) to IMD 5 (most deprived). |
Ethnicity | Split into two categories: • White and not recorded/unknown • Combined ethnic minorities |
Prescriptions (non-antibiotics) in the previous year | The number of non-antibiotic prescriptions the patient received in the previous year. This was categorised into tertiles (low, medium and high) and was done independently for each infection. Antibiotic users were included in this categorisation to allow the model to be extensible to that group, although they were not included in the datasets to which the models were fitted. |
Flu vaccinations | A binary value to indicate whether the patient had a flu vaccination in the previous year. |
Hospitalisation in the previous year | A binary value to indicate whether the patient was hospitalised in the previous year. |
Outpatient referral in the previous year | A binary value to indicate whether the patient had a hospital outpatient referral in the previous year. |
Year of consultation | Year in which the initial GP consultation took place. |
Season of consultation | • Spring (March to May) • Summer (June to August) • Autumn (September to November) • Winter (December to February) |