| Risk factor | Number of cases | Number of controls |
| CF-related diabetes* | 5 | 2 |
| History of hyponatraemia with metabolic alkalosis | 1 | 1 |
| Congenital or acquired renal impairment | 1 | 0 |
| Gastro-oesophageal reflux disease with vomiting | 1 | 2 |
| Severe sepsis* | 1 | 0 |
| Other cause of acute dehydration† | 3 | 0 |
| Concurrent non-steroidal anti-inflammatory drugs | 5 | 2 |
| Ciclosporin‡ | 2 | 0 |
| Total | 19 | 7 |
*One case with CF-related diabetes also had severe sepsis with methicillin resistant Staphylococcus aureus and required mechanical ventilation at the time of acute renal failure.
†Other causes of acute dehydration were diarrhoea and vomiting (n = 2) and a febrile illness (n = 1).
‡Ciclosporin was prescribed to two of the index cases, one for severe allergic bronchopulmonary aspergillosis (concurrent) and one for co-morbid asthma (discontinued 2 years before acute renal failure).