After the randomisation of 262 participants to the TESTING an imbalance in serious adverse events was noted between the methylprednisolone and placebo arms of the trial by the Data Monitoring Committee, mostly due to infection. As the data also suggested likely benefit on kidney outcomes, a further 240 participants will be randomised to methylprednisolone 0.4 mg/kg/day compared to matching placebo (The TESTING low-dose group). Oral sulfamethoxazole/trimethoprim will also be provided to reduce the risk of infection All participants will undergo long term follow-up until at least 160 primary outcome events are observed (expected to be an average of at least 4 years), and the effects of steroids on the risk of the composite kidney outcome will be assessed on the study population as a whole, stratified for treatment regimen so long as there is no evidence of significant heterogeneity in the efficacy at reducing the primary outcome.