Chronic kidney disease (CKD) is commonly managed in primary care, but most guidelines have a secondary care perspective emphasizing the risk of end-stage kidney disease (ESKD) and need for renal replacement therapy. In this prospective cohort study, we sought to study in detail the natural history of CKD in primary care to better inform the appropriate emphasis for future guidance.
Methods and Findings
In this study, 1,741 people with CKD stage 3 were individually recruited from 32 primary care practices in Derbyshire, United Kingdom. Study visits were undertaken at baseline, year 1, and year 5. Binomial logistic regression and Cox proportional hazards models were used to model progression, CKD remission, and all-cause mortality. We used Kidney Disease: Improving Global Outcomes (KDIGO) criteria to define CKD progression and defined CKD remission as the absence of diagnostic criteria (estimated glomerular filtration rate [eGFR] >60 ml/min/1.73 m2 and urine albumin-to-creatinine ratio [uACR] <3 mg/mmol) at any study visit. Participants were predominantly elderly (mean ± standard deviation (SD) age 72.9 ± 9.0 y), with relatively mild reduction in GFR (mean ± SD eGFR 53.5 ± 11.8 mL/min/1,73 m2) and a low prevalence of albuminuria (16.9%). After 5 y, 247 participants (14.2%) had died, most of cardiovascular causes. Only 4 (0.2%) developed ESKD, but 308 (17.7%) evidenced CKD progression by KDIGO criteria. Stable CKD was observed in 593 participants (34.1%), and 336 (19.3%) met the criteria for remission. Remission at baseline and year 1 was associated with a high likelihood of remission at year 5 (odds ratio [OR] = 23.6, 95% CI 16.5–33.9 relative to participants with no remission at baseline and year 1 study visits). Multivariable analyses confirmed eGFR and albuminuria as key risk factors for predicting adverse as well as positive outcomes. Limitations of this study include reliance on GFR estimated using the Modification of Diet in Renal Disease study (MDRD) equation for recruitment (but not subsequent analysis) and a study population that was predominantly elderly and white, implying that the results may not be directly applicable to younger populations of more diverse ethnicity.
Management of CKD in primary care should focus principally on identifying the minority of people at high risk of adverse outcomes, to allow intervention to slow CKD progression and reduce cardiovascular events. Efforts should also be made to identify and reassure the majority who are at low risk of progression to ESKD. Consideration should be given to adopting an age-calibrated definition of CKD to avoid labelling a large group of people with age-related decline in GFR and low associated risk as having CKD.
In this prospective cohort study, Adam Shardlow and colleagues report on the progression of chronic kidney disease over 5 years among patients in primary care.
Why Was This Study Done?
Chronic kidney disease affects 10%–20% of adults in most countries and is associated with multiple adverse outcomes, including increased risk of death, progression to end-stage kidney disease (requiring dialysis or kidney transplantation), and increased risk of diseases of the heart and arteries.
The risk of these adverse outcomes varies considerably, and previous studies indicate that most people with chronic kidney disease are at low risk.
Many previous studies have been conducted in large teaching hospitals and have understandably emphasized the risk of end-stage kidney disease, but the results may not be applicable to the majority with chronic kidney disease because most have mild disease, are cared for by family doctors, and are never referred to a kidney specialist.
We conducted this study to better understand the risks associated with chronic kidney disease in people cared for by family doctors in order to provide a perspective that is applicable to the majority of people affected.
What Did the Researchers Do and Find?
We individually assessed 1,741 people with mild (stage 3) chronic kidney disease at 32 family doctors’ clinics and reassessed them after 1 and 5 y.
We found that most people (34%) had stable kidney function, only a very small minority (4 people or 0.2%) developed end-stage kidney disease, and 18% evidenced less severe progression after 5 y.
Surprisingly, kidney function improved in some people (19%) to the extent that they no longer had evidence of chronic kidney disease.
What Do These Findings Mean?
Our data emphasize that the management of chronic kidney disease by family doctors should focus on identifying the minority of people who are at high risk of adverse outcomes for more intensive treatment and referral to a kidney specialist.
People at low risk should also be identified so that they can be reassured and spared unnecessary treatment or referral.
An internationally agreed definition for “remission” of chronic kidney disease is needed so that this outcome can be studied in more detail in other populations.
Our findings may not be directly applicable to populations with younger age or greater ethnic diversity.