Measuring the population burden of chronic kidney disease: a systematic literature review of the estimated prevalence of impaired kidney function

Background
Internationally, there have been substantial efforts to improve the early identification of Chronic Kidney Disease (CKD), with a view to improving survival, reducing progression and minimising cardiovascular morbidity and mortality. In 2002, a new and globally adopted definition of CKD was introduced. The burden of kidney function impairment in the population is unclear and widely ranging prevalence estimates have been reported.

Methods
We conducted a systematic literature review, searching databases to June 2009. We included all adult population screening studies and studies based on laboratory or clinical datasets where the denominator was clear. Studies reporting prevalence estimates based on at least one eGFR <60ml/min/1.73m2 or elevated creatinine above a stated threshold were included. Study design and quality were explored as potential factors leading to heterogeneity.

Results
We identified 43 eligible studies (57 published reports) for inclusion. Substantial heterogeneity was observed with estimated prevalence (0.6%-42.6%). The included studies demonstrated significant variation in methodology and quality that impacted on the comparability of their findings. From the higher quality studies, the six studies measuring impaired kidney function using estimated glomerular filtration rate in community screening samples reported a prevalence ranging from 1.7% in a Chinese study to 8.1% in a US study, with four reporting an estimated prevalence of 3.2-5.6%. Heterogeneity was driven by the measure used, study design and study population.

Conclusion
In the general population, estimated impaired kidney function, particularly eGFR 30-59ml/min/1.73m2 was common with prevalence similar to diabetes mellitus. Appropriate care of patients poses a substantial global healthcare challenge.