The aim of this study was to compare the perceived HRQOL in KTRs and HD patients. The current study has shown that KTRs were more likely to be younger, men, and with higher education level than HD patients. Younger KRTs had significantly lower MCS score than older KTRs. Conversely, younger HD patients had significantly higher MCS score than older HD patients. There were no significant differences in PCS scores by age group in either KTRs or HD patients. After controlling for sociodemographic variables, we found clinically significant differences in perceived HRQOL between KTRs and HD patients. KTRs had significantly higher perceived HRQOL scores in role-physical, bodily pain, general health, vitality, social functioning, role-emotional, mental health, physical component summary, and mental component summary than HD patients. These observed differences ranged between 15.5 points in social functioning and 34.3 points in general health. However, contrary to our expectations, KTRs had significantly lower perceived HRQOL in physical functioning than HD patients by 25 points. The magnitude of observed differences in HRQOL scores between KTRs and HD patients in the current study are considered clinically important differences based on the cut-off points for the minimal clinically important difference (3–5 points) for any health condition (27), 6–11 points for patients with stage five chronic kidney disease (28), and 15 points for patients with heart disease (29). Our observed differences between KTRs and HD patients in age, gender, and education level are consistent with those of other studies and suggest that KRTs are more likely to be younger, men, and have higher education level (30, 31).
Table 3
Adjusted differences in perceived HRQOL scores between kidney transplant recipients (n = 100) and hemodialysis patients (n = 272)
SF-36 dimensions | Group | β (BCa 95% CI)a | S.E. | Mean score (95% CI) | S.E. of mean | p value |
Physical functioning | KTRs HDPs | -24.5 (-29.9, -18.7) Ref | 3.0 - | 27.9 (22.4, 33.3) 52.3 (48.6, 56.1) | 2.8 1.9 | 0.001 |
Role-physical | KTRs HDPs | 32.6 (24.0, 41.1) Ref | 4.4 - | 67.8 (59.8, 75.7) 35.2 (29.7, 40.6) | 2.8 1.9 | 0.001 |
Bodily pain | KTRs HDPs | 24.8 (18.2, 31.4) Ref | 3.3 - | 79.6 (73.6, 85.5) 54.7 (50.7, 58.8) | 2.1 3.0 | 0.001 |
General health | KTRs HDPs | 34.3 (28.7, 39.9) Ref | 2.7 - | 57.1 (70.3, 79.9) 40.8 (37.5, 44.2) | 2.5 1.7 | 0.001 |
Physical component summary | KTRs HDPs | 16.8 (13.8, 19.9) Ref | 1.5 - | 62.6 (59.8, 65.4) 45.8 (43.9, 47.9) | 1.4 1.0 | 0.001 |
Vitality | KTRs HDPs | 20.5 (14.9, 26.6) Ref | 3.1 - | 59.8 (54.6, 64.9) 39.3 (35.8, 42.9) | 2.6 1.8 | 0.001 |
Social functioning | KTRs HDPs | 15.5 (10.1, 20.7) Ref | 2.6 - | 87.9 (82.2, 93.5) 72.4 (68.5, 76.3) | 2.9 2.0 | 0.001 |
Role-emotional | KTRs HDPs | 29.5 (20.2, 39.7) Ref | 4.8 - | 68.6 (59.8, 77.3) 39.0 (33.0, 45.1) | 4.5 3.1 | 0.001 |
Mental health | KTRs HDPs | 24.5 (17.5, 30.6) Ref | 3.2 - | 73.7 (67.5, 79.8) 49.2 (45.0, 53.4) | 3.1 2.2 | 0.001 |
Mental component summary | KTRs HDPs | 22.5 (17.6, 27.5) Ref | 2.6 - | 72.5 (67.7, 77.3) 50.0 (46.7, 53.3) | 2.5 1.7 | 0.001 |
KTRs Kidney transplant recipients, HDPs Hemodialysis patients, SE Standard error, BCa Bias corrected accelerated, CI Confidence interval, Ref Reference category. |
aSF-36 HRQOL subscales and physical and mental component summary score estimates are adjusted for age group, gender, education level, and residential area. |
One explanation of the observed higher proportion of younger individuals among KTRs than HD patients is that younger patients with end stage kidney disease are less likely to have comorbid conditions than older patients, which makes younger patients better candidates for kidney transplantation (32). Our finding of high proportion of men than women among KTRs and HD patients could be explained by the higher prevalence of non-communicable disease risk factors and the faster progression of end stage kidney disease in men more than women (33, 34). A plausible explanation for our finding of higher education level (a proxy measure for socioeconomic) among KTRs than HD patients is that socioeconomic status advantaged patients may have higher expectations for health and preference for kidney transplantation (35). Additionally, individuals with higher socioeconomic status are more likely to have lower prevalence of comorbid conditions and other contraindications for kidney transplantation, such as smoking and obesity (36). This explanation also applies to our finding of higher physical and mental health summary scores among KTRs and HD patients. The lower mental health summary score among younger KTRs found in the current study could be explained by their potential higher levels of worry about allograft survival, employment, and other economic factors (37, 38).
The findings of our study are consistent with the findings of previous studies suggesting that kidney transplantation is associated with better physical and mental HRQOL scores than other renal replacement therapies (25, 39, 40). In contrast to these findings, however, a systematic review with meta-regression, found no clinically meaningful differences between KTRs and HD patients in four dimensions of HRQOL (role physical, bodily pain, vitality, and mental health) after adjusting for age and diabetes. However, the findings of meta-regression analyses should be interpreted with caution because any observed differences aggregated across studies may not necessarily apply to individual patients within single studies (ecological fallacy). The explanations for the contradictory findings between our study and the aforementioned systematic review are largely unclear. One plausible explanation is that long-term use of immunosuppression medications by KTRs is commonly associated with important side effects, such as significant weight gain, recurrent infection, diabetes, hypertension, cardiovascular disease, and poor self-perception of physical appearance (13, 14). For example, a cohort study of nondiabetic KTRs (n = 25,837) found that 17.7% and 12.3% of KTRs who were prescribed steroid-containing and steroid-free immunosuppressive regimens developed new onset of diabetes within three years post transplantation, respectively (41). This suggests that initial improvements in some aspects of HRQOL among KTRs may decline over time. This plausible explanation is supported by the findings of previous cohort studies examining HRQOL among KTRs (17, 37, 42). For instance, a five-year prospective cohort study of 110 KTRs and HD patients found no clinically important differences between KTRs and HD patients in five dimensions of HRQOL (physical functioning, bodily pain, role-emotional, mental health, and MCS scores) by the end of follow up (42).
The present study found that KTRs had lower perceived HRQOL in physical functioning by 25 points than HD patients, which is a novel finding that, to our knowledge, has not previously been described. The exact mechanisms underlying this finding are not very clear. This is because physical functioning is determined by several factors including physical activity, physical fitness level, and other known barriers to physical activity faced by KTRs, such as fear of physical activity and allograft rejection, immunosuppression side effects, new-onset of medical comorbidities, obesity, socioeconomic factors, and inadequate self-care strategies and clinician guidance on physical exercise (43, 44). One potential explanation for our finding is that determinants and barriers of physical functioning might be more prevalent, or have greater negative impact, among KTRs in our sample as compared to other KTRs in other regions, which needs to be further explored. For example, one recent study showed that about 46% of KTRs in Palestine were unemployed (30), whereas only 6% of German KTRs were reported to be unemployed (40). Another potential explanation is that perceived HRQOL measures do not account for individual variations in expectations and actual experiences of healthcare outcomes, which may be driven by diverse factors, such as culture, spirituality, socioeconomic status, personality, and other sociodemographic factors (45). This explanation suggests that KTRs may under report their HRQOL if their high expectations for health and recovery are not met completely. However, we think that this explanation is not plausible because we would expect KTRs to under report their HRQOL in other subscales of physical and mental health subscales as well, which we did not observe. Therefore, we think that the observed lower HRQOL in physical functioning score among KTRs compared with HD patients is highly likely to be explained by the aforementioned barriers to physical functioning among KTRs and inadequate vocational and physical rehabilitation after kidney transplantation (40, 44). For example, a qualitative study among KTRs showed that about 80% and 40% of KTRs reported having a sedentary lifestyle and receiving little clinical guidance on physical exercise after transplantation, respectively (44).
The present study included a relatively large number of KTRs and HD patients from two kidney units representing 37% of patients on renal replacement therapy in the West Bank (20). The sociodemographic characteristics of participants in our study are very similar to those of other studies from Palestine and other regions (30, 31). In addition, we accounted for key predictors of HRQOL using multivariable regression analysis. Additionally, the Palestinian population is highly homogeneous in terms of ethnicity, culture, spirituality, and physical environment. This enhances the validity of our study, and therefore our findings are highly likely to be generalizable to KTRs and HD patients in Palestine. However, our findings may not generalize to other populations and regions with different healthcare system, culture, religious beliefs, ethnicity, and other socioeconomic factors influencing HRQOL.
Several limitations need to be noted regarding the present study. First, we used a cross-sectional design to address the aim of the study, and therefore, the temporality and direction of observed differences in perceived HRQOL scores between KTRs and HD patients, presumably attributed to successful kidney transplantation, cannot be established with great confidence. Nonetheless, our findings, taken together, are largely consistent with the findings of other prospective cohort studies (17, 46). Second, we collected no information on some factors which adversely affect the HRQOL among patients with end stage renal disease, such as comorbid conditions and biochemical variables, as creatinine (47). However, these factors are more prevalent among HD patients, thus lack of adjustment for those variables is not expected to attenuate the observed clinically important differences in HRQOL values between KRTs and HD patients. Third, self-reported perceived HRQOL is considered a subjective indicator and may be influenced by individual expectations of health and recovery, which may underestimate or overestimate actual healthcare outcomes.
Despite the marked improvements in various aspects of HRQOL attributed to successful kidney transplantation, healthcare professionals managing patients on renal replacement therapy should be aware that KTRs have low perceived HRQOL in physical functioning, which should be addressed and monitored closely. There is some evidence from a systematic review that poor physical capacity among KTRs is associated with poor HRQOL and increased risk of hospital admission rates, length of hospital stay, and mortality (48). For instance, the findings of a cohort study of 10,875 KTRs suggest that a modest improvement in physical functioning may decrease mortality rate by 11% among KRTs with low levels of physical functioning (49). In addition, a recent systematic review found that exercise therapy for KTRs is associated with significant improvements in HRQOL and exercise tolerance, and may improve renal allograft function (estimated glomerular filtration rate) (48). More recently, the Japanese Society of Renal Rehabilitation has published a guideline recommending exercise therapy for KTRs (50). Therefore, healthcare professionals managing KTRs should encourage KTRs to exercise regularly and give them adequate guidance on participating in exercise training programs tailored to the individual capacity. Multicenter and large longitudinal research studies are needed to better understand determinants of perceived HRQOL and examine potential interventions to enhance the HRQOL among KTRs. In addition, future research on physical and mental health related quality of life among KTRs should include objective measures and account for patients’ expectations and experiences of medical treatment outcomes to promote effective communication and shared clinical decision-making.