The primary aim of this study is to extend follow up of TESTING study participants and to assess the long-term effects of a 6-9-month course of oral methylprednisolone on End Stage Kidney Disease (ESKD), according to dose (full-dose vs reduced-dose), ethnicity (Chinese vs other) and kidney function (eGFR above and below 60 mL/min/1.73m2).

In the original TESTING study, the median follow-up for full vs reduced dose cohort was 6.1 vs 2.5 years. We learned from the TESTING trial that the composite endpoints (ESKD, 40% reduction in eGFR or death due to kidney disease) tend to start occurring 2-3 years after randomization. At the time of overall study completion, most of the reported endpoints had occurred in participants from the initial, full-dose TESTING cohort. Although we found the effect of corticosteroid is consistent in both doses, longer follow up is required to confirm the beneficial effects on clinically important renal outcomes of the apparently safer reduced reduced-dose cohort, and to confidently compare the effects across doses. As the trial is assessing the effects of a time-limited 6-9-month period of steroids, a post-trial observation cohort study is a critical, cost and resource-efficient method of answering a number of key questions:

1. Is the apparent benefit of glucocorticoid sustained over long term follow-up?
2. Does a lower dose of steroids safely produce similar benefits on long-term kidney outcomes?

The primary aim of TESTING-ON is to extend follow up of TESTING study participants and to assess the long-term effects of a 6-9-month course of oral methylprednisolone on end stage kidney disease (ESKD), according to dose (full-dose vs reduced-dose), ethnicity (Chinese vs other) and kidney function (eGFR above and below 60 mL/min/1.73m2).

The working hypothesis of TESTING-ON is that a 6-9-month course of oral methylprednisolone will lead to persistent benefits over a long period of time.

TESTING-ON is a post-trial observational study of those participants randomized into the TESTING trial who are still alive, haven't reached ESKD and didn't withdraw consent during the trial. Follow-up will continue for up to five years, with further ongoing follow-up should funding allow.

Inclusion Criteria:

1) Only participants who were randomised into the TESTING trial

Exclusion Criteria

1. Participants who have reached kidney failure requiring maintenance dialysis or kidney transplantation during the TESTING trial
2. Participants who died during the TESTING trial
3. Participants who had withdrawn their consent during the TESTING trial
4. Participants who are unable to provide consent for some other reason

The population for this study will consist of all TESTING participants who do not meet any of the exclusion criteria.