Chronic kidney disease (CKD) is a common and serious condition worldwide. It can progress to end-stage renal disease. Aging, diabetes mellitus, hypertension, and cardiovascular disease are common and significant risk factors. Because severe renal failure is incompatible with life, renal replacement therapy with hemodialysis, peritoneal dialysis, or kidney transplantation should be initiated at this stage [1].

Kidney transplantation is the renal replacement therapy of choice for the growing number of patients with end-stage renal disease (ESRD). Tremendous progress in immunosuppressive treatment has improved renal graft survival rates, while at the same time making infectious complications even more common in the kidney transplant population, with the urinary tract being the most common infection site [1].

Although kidney transplantation is recognized as the best treatment option for most patients with end-stage renal disease (ESRD) to improve both life expectancy and quality of life, it remains a complex option for the nearly 200,000 patients in the United States who have a functioning graft [2].

Among the many challenges faced by patients and health providers after kidney transplantation is the burden of hospital readmission. Around 30% of kidney transplant patients are readmitted within the first 30 days after discharge from the hospital post-transplant [3]-[6]. This rate is substantially higher than that for patients undergoing other surgeries (4% - 15%) [7]. Early hospital readmission among kidney transplant recipients is associated with a twofold increase in graft failure, a threefold increase in further readmissions, and a 50% - 75% increase in patient mortality. Furthermore, post-transplant admissions are costly (average cost, >$10,000), representing 20% of all Medicare payments for transplantation. Moreover, research suggests that up to 50% of these readmissions could be preventable. Early intervention after discharge in kidney transplant recipients has been shown to reduce early readmission; thus, reliable tools to predict hospital readmission after kidney transplantation are needed [8]. One of the most common causes of early hospital readmission is infection, and kidney transplant recipients have a cumulative incidence of infections of over 75% in the first year. The high incidence of infections is multifactorial and related in part to the surgical procedure, immunosuppressive drugs, exposure to nosocomial pathogens, and the need for devices such as urinary catheters and intravascular lines [9].

Despite improvements in immunosuppressive therapy and surgical techniques, infectious complications remain a significant cause of morbidity, and these complications, especially urinary tract infections (UTIs), have been associated with an increased risk of graft rejection and generally worse graft outcomes [10].

Although several studies have identified significant risk factors for hospitalization following kidney transplantation, including demographic, socioeconomic, clinical, transplant surgery, and utilization factors, few studies have attempted to predict post-transplant readmission, and those that did reported low accuracy (c-statistics between 0.63 and 0.71) [3][8]. One potential explanation for this poor accuracy is the variability in the causes and timing of readmission. Indeed, rejection-related or surgical complication-related readmissions are more common early post-transplant. In contrast, infection- and other comorbidity-related readmissions are the most prevalent causes of readmission later post-transplant. Finally, most studies examined the risk of first readmission post-transplantation, although an essential group of transplant recipients experiences multiple readmissions post-kidney transplantation [8].

This study confirms the high burden of hospital readmission following kidney transplantation among adult kidney transplant recipients and underscores the challenge of predicting hospital readmission in this population. This study underlines the need to select potential risk factors in light of each specific study outcome, since the importance of predictors varies based on the timing of readmission and whether we consider the first versus subsequent readmissions.

The majority of participants were male, 75% (n = 225), revealing a sharp gender imbalance that may be explained by males having greater exposure to end-stage renal disease risk factors. These results were comparable to similar studies in Spain [11] and the United States of America [12], which also reported male predominance (60.9% vs. 39.1%) and (61.2% vs. 38.8%), respectively, in patients with chronic kidney disease (CKD). Studies in Ghana [13] and Nigeria [14] also reported male predominance (65% vs. 35%) and (65.3% vs. 34.7%), respectively. This male predominance may reflect the fact that chronic kidney disease and its risk factors, such as hypertension and smoking, are more common in males than in females. Differences in health-seeking behaviors between males and females may also contribute to the observed differences in chronic kidney disease prevalence between the two sexes.

This study found that most patients were in the 40 - 59 age group (49.3%). This reflects a generally younger population, with ESRD and CKD affecting the economically productive young society between the ages of 20 and 50 years. A similar study by Okwuonu C. et al.. reported a mean age of 43 years, with most patients (53.6%) in the 40 - 60 age group [15].

The present study also demonstrated that hypertension (48.7%) was the most common cause of CKD among our participants. Several studies in Ghana [13][16][17] and Nigeria [18] have identified hypertension as the most common cause of CKD. Our study found that the rate of hospital readmission after kidney transplant was 39% (n = 117), and among them, most patients (72.6%, n = 85) were readmitted once. This rate was similar to that reported by the US registry for a cohort of 32,961 kidney transplant recipients treated by the Medicare system from 2000 to 2005; hospital readmission was 31%, ranging from 18% to 47% across transplant centers [3][19][20][21]. Our rate was also comparable to other previous studies, such as McAdams-Demarco MA et al. who reported 31% [3], Julien H et al. who reported 39% [8], Ostrem J et al. who reported 35.7% [22], and Michelle C et al. in Ohio who reported 30-day, 90-day, and 1-year HR as 31%, 41%, and 53%, respectively [23]. Although our rate was lower than those reported by Leal R et al. (49%) [9], Karima B et al. (45.5%) [24], Avila C et al. (64.9%) [25], and Jesse D et al. (48%) [26].

Among readmitted patients, infection was the leading cause of readmission after a kidney transplant. Our findings were consistent with those of Leal R et al. and Karima B et al. [24], who also reported that infection (mainly urinary tract infection) was the most common cause of readmission after kidney transplant [9]. The current study found that the recipient’s male gender (p value = 0.031) and high body mass index (p value = 0.014) were the major predisposing factors for hospital readmission after a kidney transplant. This is in accordance with the study of Avila et al., who reported that hospital readmission was lower for females compared to males (OR = 0.769, p = 0.005) and increased with high body mass index (p value < 0.001) [25].

Also, Leal R et al. found that a higher body mass index was a significant risk factor for readmission (P = 0.03) [9].

Our study also reported that hospital readmission after kidney transplantation was common among those with chronic lung diseases and diabetes mellitus comorbidities (P-value 0.000). Leal R et al. also reported that diabetes mellitus was a predictor of readmission after kidney transplantation (P = 0.02) [9].

Another critical risk factor for hospital readmission after kidney transplantation in our study group was dialysis before transplantation, particularly peritoneal dialysis and peritoneal combined hemodialysis (p = 0.003). These findings were consistent with those reported by Ostrem J et al. in the United States, who found that patients on dialysis before transplant had a readmission rate of 28.2%, compared with 5.6% for those not on dialysis (p = 0.037) [22].

Not surprisingly, post-transplantation follow-up was significantly associated with hospital readmission (P-value 0.000). Readmission was more frequent among patients who missed post-transplantation follow-up (Miss < 50% = 100% and Miss < 25% = 72.4%) than among those who did not miss follow-up (P-value 0.000).

This study demonstrated that readmission was significantly more frequent among recipients who received kidneys from older donors (>60 years) than among others (P value 0.003). This finding aligns with the study by Leal et al., which showed that older donors were significantly associated with readmission (P = 0.007) [9]. In addition, readmission was significantly more frequent among recipients who received kidneys from 2nd-degree related donors (55%), parent donors (53.8%), and partner donors (husband/wife) (45%) than among other relationships (P value 0.034).

Remarkably, readmission was more frequent among patients with high (100%) and intermediate (84.6%) immunological risks than among those with low immunological risks (P-value 0.000). McAdams-Demarco reported similar findings.

This study concludes that the hospital readmission rate after kidney transplantation among Sudanese recipients was high. Hospital readmission was significantly associated with male gender, body mass index, diabetes mellitus, and chronic lung diseases as comorbidities, dialysis before kidney transplant (peritoneal dialysis and peritoneal combined hemodialysis), and missing post-kidney transplantation follow-up among recipients’ characteristics.

Among donor characteristics, older-aged donors (>60 years) and 2nd-degree related donors were significant risk factors for hospital readmission. Moreover, among kidney transplant characteristics, hospital readmission was frequent in patients with high and intermediate immunological risk.

Relevant and addresses a major concern in Sudan and worldwide. Filling a knowledge gap that has the potential to reduce hospital readmissions and improve the prognosis and quality of life for kidney transplant recipients. Limited complementary information could be obtained from the records at Sudanese kidney transplant centers. The cross-sectional nature of the study revealed significant associations; however, it did not establish causal relationships among the variables.

Hospital readmission was associated with reduced graft and patient survival; thus, highly accurate predictive models of post-transplant readmission are needed to guide the implementation of targeted interventions to reduce the burden of post-transplant readmission after kidney transplantation. A specific preventive program, based on infection prevention and graft function monitoring, should be established to prevent and minimize rehospitalizations. Prospective multicenter studies with detailed recipient-level data are needed to identify additional recipient factors and modifiable center-level factors that may reduce the rate of rehospitalization in this vulnerable and unique patient population.

Dr. Osman Mansour Abdalla, Senior Consultant Psychiatrist: Logistic, moral, and social support.