As the overall burden of kidney disease increases, there is a need for increased screening, early identification and management of cases to prevent adverse outcomes from the disease processes. In this study, we estimated the prevalence of abnormal kidney function and 90-days outcomes among patients admitted on the medical wards in Masaka RRH between September and November 2020. We found that at least one in every three patients had abnormal kidney function with decreased eGFR contributing the highest proportion of the abnormal function. The 90-days mortality among the patients with abnormal kidney function was high with more than half of the patients dying within this period. In addition, progression to CKD was high among this population, with one in ten participants progressing to CKD. These results show that there is high burden of abnormal kidney function among patients admitted to medical wards at this regional referral facility in Uganda and highlight the need for mechanisms to screen for abnormal kidney function at these facilities to accelerate medical response.
We observed a high prevalence of abnormal kidney function in this study and given that the patients were admitted on the medical wards due to other disease conditions, the abnormal function observed could be due to multiple etiologies. Many of the patients with abnormal kidney function had known risk factors for kidney disease including advanced age, comorbidities including HIV, diabetes mellitus and hypertension, as well as risky lifestyles like smoking and alcohol consumption (12-14).
Irrespective of the original cause of abnormal kidney function, its high prevalence is of concern as this can easily progress to CKD, kidney failure and death in this population. Indeed, the observed prevalence is higher than what has been described previously in Uganda. A study by Nyende et al in 2020 estimated the prevalence of abnormal kidney function at 2.5% among HIV patients attending an out-patient clinic (15) and another study conducted in the general population which estimated the prevalence of abnormal eGFR at 19.8% (16). The differences observed in our estimates compared to these estimates could be mainly because of the differences in populations studied, different definitions of abnormal kidney function and the different methods used to determine eGFR.
Mortality among patients with abnormal kidney function was high at 69.4% thus more than half of the patients had died within 90-days. This was all cause mortality, hence could be accounted for by other illnesses including sepsis, advanced HIV/AIDS, uncontrolled diabetes mellitus and hypertensive complications. This high mortality is similar to findings from several studies; Machado et al, 2014 in Brazil, found a 30-days mortality of 66% among patients with abnormal kidney function (Machado, Nakazone, & Maia, 2014). A collaborative meta-analysis of kidney disease population cohorts showed a positive association between lower eGFR category and mortality (17) and during another pooled analysis of community-based studies including Atherosclerosis Risk in Communities Study (ARIC), the Cardiovascular Health Study (CHS), the Framingham Heart Study (FHS), and the Framingham Offspring Study (Offspring), subjects with CKD (eGFR: 15 to 60 ml/min/1.73 m2) had a 36% excess risk for all-cause mortality (18). Another prospective cohort study in Tanzania by found mortality rates of 56.6% after 3 months (19). These studies show that patients with abnormal kidney function are at high risk of death.
In our study the very high mortality was probably because most patients with CKD or kidney failure were not able to access prompt ideal care including hemodialysis or transplant for those who had kidney failure thus may have partly died of kidney failure related complications in addition to their primary comorbidities.
The incidence of CKD among the patients with abnormal kidney function was also high with one in every ten patients having CKD after 90-days of follow-up. CKD was confirmed using decreased eGFR of < 60 mls/minute/1.73m² and proteinuria of ≥1+ both at baseline and after 90-days during follow up. This is in agreement with findings of other studies about outcomes for patients with abnormal kidney function. A study among patients attending hypertension clinic of Mulago National Referral Hospital also found the prevalence of CKD was 17.2 % after 90-days of follow up (5). However finding of our study differ from findings of a prospective study conducted in the adult medical wards of a teaching hospital in Tanzania where a very high prevalence of CKD was found to be 69.5% after three months follow up of patients with reduced eGFR of < 60ml/min/1.73m² (19). The lower prevalence in our study could partly be related to the very high mortality for our study patients with decreased eGFR at baseline and traditional risk factors for CKD which a significant number of these patients had including diabetes mellitus, hypertension and HIV/AIDS.
The study is not without limitations. First, we only followed up only participants with abnormal kidney function thus we are unable to compare outcomes with those patients having normal kidney function. Although this may affect the mortality outcome in that mortality may be comparable among the two groups, we are confident the CKD findings would be higher in the two groups given that abnormal kidney function is in the pathway of CKD. Second, we never performed renal ultrasound scan which would enable us to diagnose more patients with CKD basing on renal structural abnormalities and lastly, our study was not powered to establish factors associated with 90-days outcomes at follow-up period due to the small sample size, thus one may urge that high mortality for patients with abnormal kidney function could have been attributed to other comorbid illnesses among some patients.