Time to differentiate 'decreased kidney function' from 'kidney disease': towards improving the definition of chronic kidney disease

Presence of early CKD-related metabolic complications predict progression of stage 3 CKD: a case-controlled study

BACKGROUND

Only a subset of patients who enter stage 3 chronic kidney disease (CKD) progress to stage 4. Identifying which patients entering stage 3 are most likely to progress could improve outcomes, by allowing more appropriate referrals for specialist care, and spare those unlikely to progress the adverse effects and costliness of an unnecessarily aggressive approach. We hypothesized that compared to non-progressors, patients who enter stage 3 CKD and ultimately progress have experienced greater loss of renal function, manifested by impairment of metabolic function (anemia, worsening acidosis and mineral abnormalities), than is reflected in the eGFR at entry to stage 3. The purpose of this case-controlled study was to design a prediction model for CKD progression using laboratory values reflecting metabolic status.

METHODS

Using data extracted from the electronic health record (EHR), two cohorts of patients in stage 3 were identified: progressors (eGFR declined >3 ml/min/1.73 m2/year; n=117) and non-progressors (eGFR declined <1 ml/min/1.713 m2; n=364). Initial laboratory values recorded a year before to a year after the time of entry to stage 3, reflecting metabolic complications (hemoglobin, bicarbonate, calcium, phosphorous, and albumin) were obtained. Average values in progressors and non-progressors were compared. Classification algorithms (Naïve Bayes and Logistic Regression) were used to develop prediction models of progression based on the initial lab data.

RESULTS

At the entry to stage 3 CKD, hemoglobin, bicarbonate, calcium, and albumin values were significantly lower and phosphate values significantly higher in progressors compared to non-progressors even though initial eGFR values were similar. The differences were sufficiently large that a prediction model of progression could be developed based on these values. Post-test probability of progression in patients classified as progressors or non-progressors were 81% (73% - 86%) and 17% (13% - 23%), respectively.

CONCLUSIONS

Our studies demonstrate that patients who enter stage 3 and ultimately progress to stage 4 manifest a greater degree of metabolic complications than those who remain stable at the onset of stage 3 when eGFR values are equivalent. Lab values (hemoglobin, bicarbonate, phosphorous, calcium and albumin) are sufficiently different between the two cohorts that a reasonably accurate predictive model can be developed.

Healthy behaviors, risk factor control and awareness of chronic kidney disease

BACKGROUND/AIMS

The association between chronic kidney disease (CKD) awareness and healthy behaviors is unknown. We examined whether CKD self-recognition is associated with healthy behaviors and achieving risk-reduction targets known to decrease risk of cardiovascular morbidity and CKD progression.

METHODS

CKD awareness, defined as a 'yes' response to 'Has a doctor or other health professional ever told you that you had kidney disease?', was examined among adults with CKD (eGFR <60 ml/min/1.73 m(2)) who participated in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Odds of participation in healthy behaviors (tobacco avoidance, avoidance of regular nonsteroidal anti-inflammatory drug use, and physical activity) and achievement of risk-reduction targets (angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use, systolic blood pressure control and glycemic control among those with diabetes) among those aware versus unaware of their CKD were determined by logistic regression, controlling for sociodemographics, access to care and comorbid conditions. Systolic blood pressure control was defined as <130 mm Hg (primary definition) or <140 mm Hg (secondary definition).

RESULTS

Of 2,615 participants, only 6% (n = 166) were aware of having CKD. Those who were aware had 82% higher odds of tobacco avoidance compared to those unaware (adjusted OR = 1.82, 95% CI 1.02-3.24). CKD awareness was not associated with other healthy behaviors or achievement of risk-reduction targets.

CONCLUSIONS

Awareness of CKD was only associated with participation in one healthy behavior and was not associated with achievement of risk-reduction targets. To encourage adoption of healthy behaviors, a better understanding of barriers to participation in CKD-healthy behaviors is needed.