| Abstract|| |
We studied the impact of residual renal function (RRF) on clinical outcome and quality of life in 61 patients on peritoneal dialysis (PD). They were assigned to two groups, at the time of initiation of PD, based on their estimated glomerular filtration rate (eGFR). The high RRF group had eGFR ≥5 mL/min/1.73 m and the low RRF group hade GFR <5 mL/min/1.73 m. All patients were followed up at regular intervals for clinical and biochemical variables. Baselines characteristics including age, sex, body mass index and cause of the kidney disease were similar in both groups. The high RRF group had a higher rate of continuous ambulatory peritoneal dialysis discontinuation. The incidence of peritonitis was higher in the low RRF group. Other infections (cellulitis, gastroenteritis, sepsis) were more common in patients with low RRF, compared to the high RRF group. The quality of life as assessed by depression score, restless leg syndrome, and sleep quality were poor in patients with reduced RRF. We found that a high RRF at the time of initiation of PD, significantly decreased the incidence of infections, depression, better nutrition, and lower levels of alkaline phosphatase; providing indirect evidence of better renal clearance of phosphorous, in those with preserved RRF.
|How to cite this article:|
John MM, Gupta A, Sharma RK, Kaul A. Impact of residual renal function on clinical outcome and quality of life in patients on peritoneal dialysis. Saudi J Kidney Dis Transpl 2017;28:30-5
|How to cite this URL:|
John MM, Gupta A, Sharma RK, Kaul A. Impact of residual renal function on clinical outcome and quality of life in patients on peritoneal dialysis. Saudi J Kidney Dis Transpl [serial online] 2017 [cited 2017 Aug 24];28:30-5. Available from: http://www.sjkdt.org/text.asp?2017/28/1/30/198109
| Introduction|| |
The preservation of residual renal function (RRF) has become of paramount importance to nephrologists in the clinical management of patients with the end-stage renal disease. Many studies have found that RRF is more important than overall adequacy of dialysis (as assessed by total small solute clearance) in patient survival and to a lesser extent in technique survival in patients on continuous ambulatory peritoneal dialysis (CAPD). , , Other beneficial effects of preserving RRF are lower risk of death in PD patients, , reduction in blood pressure, better ultrafiltration, better volume control, better middle molecule clearance (as assessed by lower serum beta 2 microglobulin level, low phosphate, and low urate levels) better anemia correction, higher bicarbonate levels, favorable lipid profile, less inflammatory milieu, and low risk of CAPD peritonitis. , , , , , , Preserved RRF also has an inverse relationship with vascular calcification and cardiac hypertrophy. In PD patients, it has been shown to provide a slower decline in RRF, as compared with HD. ,
Numerous factors have been associated with loss of RRF which include: male gender, diabetes, hemodialysis, nonwhite race, and chronic heart failure. The factors which are associated with preservation of RRF include PD and use of angiotensin converting enzyme inhibitors. Male gender, increased body mass index (BMI), diabetes, heart failure, diastolic hypertension, severe proteinuria, and a high peritonitis rate are the major predictors for loss of RRF.
The original CANUSA study suggested that it is the total (peritoneal and renal) small solute clearance that was a significant predictor of mortality. However, the reanalysis by Bargman et al, compared renal small solute clearance with volume of urine and found that every increment of 5 mL/1.73 m per week in residual kidney glomerular filtration rate (GFR) was associated with a 12% reduction in the relative risk of death, whereas every 250 mL of urine output daily was associated with 36% reduction in mortality. Interestingly, it was diuresis (not ultrafiltration or total fluid removal) that was a stronger predictor of GFR itself. The Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), conducted in 2003, showed a death risk reduction of 12% and a combined death-technique failure risk reduction of 10% per 10 L per week per 1.73 m2 of creatinine clearance suggesting that RRF preservation and the delivered Kt/V were both positively associated with improved survival. However, the effect of RRF appeared to be stronger than dialysis dose delivered.
Literature is ripe with observations that the preservation of RRF is of paramount importance toward the preservation of many dimensions of quality of life, especially vitality, sleep disorders, physical functioning, kidney disease-specific symptoms.
This is a prospective longitudinal study to record the effects of RRF at the time of initiation of peritoneal dialysis (PD) in our patient's clinical health and overall quality of life.
| Materials and Methods|| |
All consecutive patients receiving PD since the initiation of RRT between January 2012 and December 2013 were included. They were followed up till January 2015. The study was carried out at Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India, which is a tertiary referral center.
A total number of 61 patients were enrolled after obtaining their consents. They were assigned to two groups, at the time of initiation of PD, based on their estimated GFR (eGFR; as assessed by modified diet in renal disease (4 variable equation); high RRF group (with eGFR ≥5 mL/min/1.73 m2) and low RRF (with eGFR <5 mL/min/1.73 m2). Thirty patients were in the high RRF group and 31 patients in the low RRF.
All patients were followed up at regular intervals, beginning at the time of initiation of PD (0 visit), 3, 6, 12, and 18 months.
At each visit, a record of the following clinical and biochemical parameters was made: weight, BMI, BP, urine output, eGFR (calculated using the modified modification of diet in renal disease formula), ultrafiltration, serum albumin, hemoglobin, serum calcium, serum alkaline phosphatase (ALP), serum phosphorous.
Parathyroid hormone (PTH) and Vitamin D, levels were measured at 0, 6, and 18 months.
During the study, number of peritonitis events were recorded (CAPD peritonitis was defined as CAPD fluid effluent turbidity with clinical symptoms and signs of peritonitis and CAPD fluid count of >100 cells/mL, with or without CAPD fluid culture positivity, requiring intraperitoneal antibiotics of 14 days duration). In addition, other significant infections such as lower respiratory infections, cellulitits, and gastroenteritis were recorded.
Number of patients discontinuing CAPD because of either catheter infection or technique failure were recorded.
Between six and 12 months after the initiation of dialysis, sleep quality assessment was carried out using the Pittsburgh Sleep Quality Initiative questionnaire and restless leg syndrome was scored using the International Society of Restless Leg Syndrome (RLS) Study group criteria.
Depression was assessed during the similar time frame, using the Becks Depression Score and nutritional status was assessed using the Subjective Global Assessment score, during the above-mentioned interval.
All patients initiated on CAPD who were over 18 years of age at our center were enrolled. We excluded from the study patients who died within three months of initiation of CAPD.
According to the Pittsburgh Sleep Quality Initiative questionnaire scoring system, a royal score of >5 indicated poor sleep quality.
Statistical analysis was done using institution Statistical Package for Social Sciences (SPSS) software version 18.0 (SPSS Inc, Chicago, IL, USA). Nonparametric variables were assessed by Mann-Whitney U-test and parametric variables by independent t-test. P <0.05 was considered statistical significance.
| Results|| |
Baselines characteristics including age, sex, BMI, and native kidney disease were similar in both groups. The number of patients who discontinued CAPD were six (20%) in the high RRF group and 10 (32.3%) in low RRF group. Ten (33.3%) patients in high RRF group had at least one episode of peritonitis whereas 11 (35.4%) of patients in the low RRF group had peritonitis.
The incidence of lower respiratory tract infections was 15 (50%) in high RRF group and 16 (51.6%) in low RRF group.
Ten (33.3%) patients in high RRF group had other infections compared to 19 patients (61.3%).
Three patients (10%) in high RRF group died during the study period compared to group six patients (19.4%) in the low RRF group.
As assessed by PSQI, in high the RRF group, 14 patients (46.7%) had normal sleep quality score, eight (26.7%) had mild sleep disturbances and eight (26.7%) had moderate sleep disturbances, and none had severe sleep disturbances. In low RRF group, 13 patients (41.9%) had normal score, six (19.4%) had mild sleep disturbances, and 11 (35.5%) had moderate sleep disturbances, and one (3.2%) had severe sleep disturbances.
Fifteen patients (50%) in the high RRF group 15 had normal depression score, 10 (33.3%) had mild depression and five (16.7%) had moderate depression, and none had severe depression. In low RRF group, eight patients (25.8%) had normal score, 17 (54.8%) had mild depression, four (12.9%) had moderate depression and two (6.5%) had severe depression.
Using the International Society of Restless Leg Syndrome Study group criteria, we found that in the high RRF group, 12 patients (40%) had normal score, 14 (46.7%%) had mild RLS, and four (13.3%) had moderate RLS and none had severe RLS. In low RRF group, nine patients (29%) had normal score, 15 (48.4%) had mild RLS and seven (22.6%) had moderate RLS, and none had severe RLS.
Nutritional status as assessed by SGA score at initiation and after six months of CAPD therapy. In the high RRF group, only one patient (3.2%) had good SGA score at initiation and three patients (10%) had good SGA score after six months in low RRF group only one patient (3.2%) had good SGA score at initiation and four patients (12.9%) had good SGA score after six months.
As evident from the above table, the variables which reached statistically significant value after analysis, were very few, namely, eGFR at 3rd month which was high in high RRF group, depression as assessed by BDS with patients in high RRF group having less incidence of depression, albumin at 6th month being low in low RRF group and ALP level at one year with levels low in high RRF group. eGFR at 6th month and one year were high in high RRF group it did not reach statistically significance. Patients in high RRF group had good PSQI score and less number of patients had moderate degree of sleep disturbances when compared with patients in low RRF group, though it was not statistically significant. Rest of the variables had no statistically significance ([Table 1], [Table 2] and [Table 3]).
|Table 2. The International Society of RLS Study groups criteria score for RLS scoring are as follows.24|
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|Table 3. Clinical and biochemical variables in high versus low RRF groups.|
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| Discussion|| |
Baselines characteristics including age, sex, BMI, and native kidney disease were similar in both groups. The number of patients who discontinued CAPD were six (20%) in high RRF group and 10 (33.3%) in low RRF group. Among the high RRF group, 33.3% of the patients in had at least one episode of peritonitis compared to 36.7% patients in the low RRF group. Other reports have also shown the association of low RRF with peritonitis. Incidence of lower respiratory tract infections was 15 (50%) in high RRF group and 16 (51.6%) in low RRF group. Patients with low RRF also had a higher incidence of other infections such as cellulites, gastroenteritis, and sepsis in a greater proportion as compared to those with a high RRF (61.3% in the low RRF group versus 33.3% in high RRF group). Thus, a poor RRF at the start of PD poses as a surrogate marker for the poor overall condition and an impaired immune competence of PD patients.
We observed a higher mortality rate among patients with a low RRF at the time of dialysis initiation when compared with those who had a preserved RRF (19.4% versus 10%). We found that more patients in the high RRF group had a normal sleep score (46.7% vs. 41.9%). The NECOSAD study revealed that the presence of RRF has a positive influence on most dimensions of quality of life, especially physical functioning, sleep disorders and kidney-specific symptoms, whereas PD clearance showed no effects on any quality of life dimensions.
We also found that worse depression scores were seen in the high RRF group. In a study from Korea, similar observations were made. Using the restless leg syndrome as assessed by The International Society of Restless Leg Syndrome Study group criteria, we found that restless leg syndrome was more common and more severe in the in the low RRF group. Similar findings were previously reported. We found no difference in the two groups with respect to the nutritional status. This is contrary to several reports in literature that show that a good RRF and PD, positively impacts the nutritional status of patients.
To summarize, we found that patients in the high RRF group, had a statistically significant high eGFR at 3rd month from initiation of PD and continued to remain high at 6th month and one year, as compared to the low RRF group; although this did not attain statistical significance. Patients with low RRF suffered greater prevalence of depression, and had a lower serum albumin, as compared to patients with high RRF. Furthermore, serum ALP level at one year was low in high RRF group. Literature suggests that renal phosphate clearance is optimized by maintaining RRF in dialysis patients, and declines progressively with loss of RRF. In keeping with this, we hypothesize, that, good renal phosphorous clearance in the high RRF group, decreased the stimulation of inorganic and similarly ALP levels, accounting for our finding of margi-nally low phosphorous and PTH levels, and consequently, a low ALP level, in the high RRF group.
| Conclusion|| |
Our study concludes that preservation of RRF is an essential marker of patient survival and, to a lesser extent, technique survival during chronic PD therapy. Beginning renal replacement therapy with poor RRF can unleash serious clinical hazards including life threatening volume overload and cardiac dysfunction. This emphasizes the need preservation of RRF and peritoneal membrane structure and function. Avoidance of nephrotoxic drugs and the use of neutral pH PD solutions, more biocompatible PD regimes may help in better preservation of RRF.
Conflict of interest: None declared.
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Manns Manohar John
Department of Nephrology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh
[Table 1], [Table 2], [Table 3]