Translating chronic kidney disease epidemiology into patient care: the individual/public health risk paradox

Background. Applying the Kidney Disease Outcomes Quality Initiative definitions of chronic kidney disease (CKD), it appears that CKD is common. The increased recognition of CKD has brought with it the clinical challenge of translating into practice the implications for the patient and for service planning. To understand the clinical relevance and translate that into information to support individual patient care and service planning, we explored clinical outcomes in a large British CKD cohort, identified through routine opportunistic testing, with a 6-year follow-up (similar to 13 000 patient-years).

Methods. A cohort had previously been identified with CKD-sustained reduced eGFR over at least 3 months and case note review. Six-year (13 339 patient-years) follow-up for renal replacement therapy (RRT) initiation and death was achieved through data linkage. Age- and sex-specific mortality rates were compared to the general population.

Results. Of 3414 individuals (most Stage 3b-5), median age 78.6 years, followed for 13 339 patient-years, 170 (5%) initiated RRT and 2024 (59%) died without initiating RRT. RRT initiation rates decreased with age from 14.33 to 0.65 per 100 patient-years among those aged 15-25 and 75-85 years at baseline but the actual numbers initiating RRT increased from 6 to 34, respectively. RRT initiation rates were lower for female sex, absence of macroalbuminuria and less advanced CKD stage. Mortality rates increased with age from 2 to 34 per 100 patient-years for those aged 15-45 and > 85 years at baseline, an excess of 2 and 17 per 100 patient-years over that of the general population, respectively. However, the increase in relative risk was 19-fold for those aged 15-45 years and just 2-fold in those > 85 years. These data have been converted into simple tools for considering individual patients' risk and informing service planning.

Conclusions. The contrast between relative and absolute risk for both RRT initiation and mortality by age group illustrates the difficulties for planning services. The challenge that now faces clinicians is how to appropriately identify which elderly patients with CKD are at high risk of poor outcome.