CKD of undetermined aetiology: Tens of thousands of premature deaths yet too many unknowns remain

Tens of thousands of working-age adults have been dying from unexplained end-stage renal disease (ESRD) in Central America and South Asia. As the cause of this chronic kidney disease (CKD) remains unknown, the condition(s) (a unified aetiopathology has not been confirmed) has been termed ‘CKD of undetermined aetiology’ (CKDu). ‘CKD of non-traditional aetiology’, ‘chronic interstitial nephritis in agricultural communities’, ‘Mesoamerican nephropathy’, ‘Sri Lankan agricultural nephropathy’ and ‘Uddanam nephropathy’ are also used, but here we use the term CKDu. The first reports of CKDu, almost 20 years ago, were based on observations of an excess of working-age adults from agricultural communities in El Salvador and Sri Lanka receiving dialysis, but without a diagnosis explaining their ESRD [1, 2]. Available population-level data now support a high prevalence of renal dysfunction in the absence of known risk factors in Central America and South Asia [3–5], but the global extent of the problem remains unclear (Figure 1). Lack of access to renal replacement therapy (RRT) in many affected areas means that death from ESRD is common

Defining measures of kidney function in observational studies using routine healthcare data:methodological and reporting considerations

The availability of electronic health records and access to a large number of routine measurements of serum creatinine and urinary albumin enhance the possibilities for epidemiologic research in kidney disease. However, the frequency of health care use and laboratory testing is determined by health status and indication, imposing certain challenges when identifying patients with kidney injury or disease, when using markers of kidney function as covariates, or when evaluating kidney outcomes. Depending on the specific research question, this may influence the interpretation, generalizability, and/or validity of study results. This review illustrates the heterogeneity of working definitions of kidney disease in the scientific literature and discusses advantages and limitations of the most commonly used approaches using 3 examples. We summarize ways to identify and overcome possible biases and conclude by proposing a framework for reporting definitions of exposures and outcomes in studies of kidney disease using routinely collected health care data