An Observational Study to Learn More How Chronic Kidney Disease Gradually Changes Over Time in Adults Using Electronic Healthcare Records (CKD Natural History Study)

This is an observational study in which the health data of people with chronic kidney disease are studied using electronic healthcare records. In observational studies, only observations are made without participants receiving any advice or any changes to healthcare.

Chronic kidney disease (CKD) is a condition in which the kidney's ability to work properly gradually decreases over time. This causes a buildup of waste in the body and can lead to loss of kidney function over the long term. CKD is divided into different stages based on how well the kidneys are filtering the blood.

CKD is known to increase the risk of developing serious health problems such as serious heart problems, irreversible damage to kidneys requiring either dialysis or a kidney transplant (end stage kidney disease, ESKD), and early death. However, there is limited information available about how often heart problems occur in people with different stages of CKD, and how a history of heart problems might affect future risks for CKD patients.

The purpose of this study is to collect more information on how CKD changes over time for people at different CKD stages and how it affects their heart and kidneys.

The main information that researchers will collect in this study:

changes in kidney function (worsening or improvement).

Other information that researchers will collect:

patient characteristics for each stage of CKD,

the length of time for serious heart-related conditions to occur,

the length of time it takes for CKD to progress to kidney failure,

the length of time for occurrence of deaths due to any causes, and

the length of time it takes for serious heart-related conditions and kidney failure to occur.

This study will include CKD patients above 18 years of age. Researchers will review electronic healthcare records to identify CKD patients in two ways:

using disease codes for CKD and

using lab results which show abnormal kidney function.

The data will come from participants' information stored in an electronic healthcare records database called Merative Explorys database Electronic Medical Record (EMR) in the United States of America.

The research will cover the period from January 2010 up to December 2019.

Researchers will track individual patients' data and will follow them for a maximum of 5 years or until they experience certain events like changes to their CKD stage, kidney failure, serious heart-related conditions, or death.

In this study, only available data from routine care is analyzed. No visits or tests are required.


Eligibility Criteria:
Inclusion criteria

* \>18 years of age
* At least 12 months of look back period
* For Diagnosed cohorts - ICD codes for CKD diagnosis
* For Lab based cohorts - Two abnormal lab measures of eGFR or uACR/uPCR using LOINC codes.

  * Patients were included if they had the same type of test (Modification of Diet in Renal Disease (MDRD) only, CKD Epidemiology Collaboration (CKD EPI) only, Unspecified only) to estimate eGFR throughout their history because the estimation varies depending on the test used which would affect the CKD staging.

Exclusion criteria

* Birth year absent.
* Patients without any demographic information were excluded
* Patients with history of ESKD
* For Lab based cohorts:-

  * Patients were excluded if they had an incorrect test for eGFR identified by LOINC code for e.g. formula for wrong gender (Females with male MDRD formula) or wrong ethnicity (Blacks with white MDRD formula)
  * Patients with mixed types of approaches to calculate eGFR (e.g. MDRD, EPI etc.) in their history were excluded. (\<20 patients)
  * We exclude lab results if the loinc code specific for ethnicity and gender does not match the patient demographics.