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Saudi Journal of Kidney Diseases and Transplantation
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Table of Contents   
ORIGINAL ARTICLE  
Year : 2015  |  Volume : 26  |  Issue : 3  |  Page : 468-476
Effect of vitamin C supplementation on marital satisfaction in patients undergoing hemodialysis: A randomized, double-blind and placebo-controlled trial


1 Nephrology and Urology Department, Baqiyatallah University of Medical Sciences, Tehran, Iran
2 Department of Medical Surgical Nursing, Baqiyatallah University of Medical Sciences, Tehran, Iran

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Date of Web Publication20-May-2015
 

   Abstract 

One of the common problems in patients on hemodialysis (HD) is marital dissatisfaction. Because anemia and fatigue are two important factors for marital dissatisfaction, and vitamin C can ameliorate both of them, we carried out this study to evaluate the effect of vitamin C on marital satisfaction among HD patients. This randomized, placebo-controlled, double-blind and parallel-group trial was conducted on 62 HD patients. The MFI-20 and ENRICH questionnaires were completed at the start and end of study. Required laboratory parameters including serum levels of hemoglobin (Hb), hematocrit (Hct) and ferritin were also measured at the start and at the end of the study. In the intervention group, 250 mg of vitamin C was injected intravenously immediately at the end of each HD session three times a week for eight consequent weeks. In the control group, placebo saline was injected. There was a significant change in the level of fatigue (P = 0.01) and the serum levels of Hb (P = 0.006) and Hct (P = 0.02). The mean of the marital satisfaction score increased significantly in the intervention group (P = 0.001): Baseline score of 35.7 ± 5.10 versus a final score of 38.0 ± 5.30. However, the mean of marital satisfaction score decreased in the control group: Baseline 37.1 ± 7.10 versus a final score of 34.7 ± 7.40. Our findings suggest that vitamin C supplementation can modify the marital satisfaction. Further studies are recommended.

How to cite this article:
Biniaz V, Tayebi A, Ebadi A, Sadeghi S, Einollahi B. Effect of vitamin C supplementation on marital satisfaction in patients undergoing hemodialysis: A randomized, double-blind and placebo-controlled trial. Saudi J Kidney Dis Transpl 2015;26:468-76

How to cite this URL:
Biniaz V, Tayebi A, Ebadi A, Sadeghi S, Einollahi B. Effect of vitamin C supplementation on marital satisfaction in patients undergoing hemodialysis: A randomized, double-blind and placebo-controlled trial. Saudi J Kidney Dis Transpl [serial online] 2015 [cited 2021 Jun 14];26:468-76. Available from: https://www.sjkdt.org/text.asp?2015/26/3/468/157312

   Introduction Top


End-stage renal disease (ESRD) is one of the most common chronic diseases. [1],[2],[3],[4],[5] One of the frequent problems in patients suffering from ESRD is marital dissatisfaction and sexual dysfunction. [6] Marital satisfaction for married people is the most prominent contributor of life satisfaction and self-esteem. [7] Although marital dissatisfaction is not synonymous with sexual dysfunction, it is significantly associated with sexual dissatisfaction. [8],[9],[10]

Marital dissatisfaction impairs family dynamics processes. [11],[12] It is one of the predictive factors of marital quality, [13] physical health, psychological well-being [14] and quality of life. [15] It also severely links with lower health outcome, depression and anxiety. [11],[16],[17]

Marital satisfaction in patients undergoing hemodialysis (HD) is significantly lower than healthy individuals; [18],[19] 81.4% of HD patients suffer from a marital dissatisfaction, [20] due in 60-80% of them to some level of sexual dysfunctions after the inception of therapy. [21]

In addition to depression, anxiety, hormonal and psychological disturbances, [15] drug consumption and sleeping disorders, [19] anemia and fatigue are two main factors of marital dissatisfaction in HD patients. [22]

Although several studies have examined methods to reform marital and sexual dissatisfaction hitherto, [23] but we have not found any study that has reported of the influences of vitamin C on marital satisfaction in HD patients. Vitamin C is a water-soluble vitamin that can ameliorate both anemia [24],[25],[26] and fatigue. [27],[28] Vitamin C deficiency is also a prevalent complication in patients undergoing HD; [29],[30] however, it is not clear whether vitamin C deficiency is the cause or the consequence of chronic kidney diseases. [31] Vitamin C is required for the collagen, L-carnitine and certain neurotransmitters' bio-synthesis; it is also involved in protein metabolism. [32] Vitamin C is also a significant physiological antioxidant and has been shown to stimulate other antioxidants within the body, including vitamin E. [33] Furthermore, vitamin C plays a key role in the immune function [34] and improves the absorption of non-heme iron. [35] Because humans are not able to synthesize vitamin C endogenously, it is considered a vital dietary supplement. [36]

Toxicity of vitamin C is low and has no serious side-effects. Gastrointestinal disturbances such as nausea, vomiting and diarrhea are the most common grievances of high intakes of vitamin C. Although vitamin C contributes to urinary oxalate excretion, it is not clear whether large doses of vitamin C can actually increase the potential for the formation of kidney stones, especially in individuals with hyperoxaluria. A few studies also claimed that the enhancement of non-heme iron absorption by high doses of vitamin C could lead to excess iron absorption and exacerbate iron overload in individuals with hereditary hemochromatosis. [37] Because of concerns about hyperkalemia [38] and oxalosis [39] in the HD patients, prescriptions of vitamin C are restricted to 10-70% of these patients. [40],[41]

Although some practitioners are currently using doses of 1000-3000 mg/week of vitamin C, [42] we have not found a systematic study or any case report in the recent years that reported oxalosis in HD patients as a result of vitamin C supplementation. [43]

We aimed from this study to evaluate the effect of vitamin C on the marital satisfaction among the HD patients.


   Materials and Methods Top


This study was conducted as a randomized, placebo-controlled, double-blind and parallel-group trial on chronic HD patients from October 2012 to January 2013.

Sixty-two volunteer patients were enrolled from two HD units in two hospitals in an urban area of Iran. Available sampling was used to select the patients for the study. Then, the samples were randomly distributed by a lottery method into two equal groups (simple random sampling); the intervention group received vitamin C and the control group received placebo.

Both groups were not significantly different in the clinical parameters, including age, sex, weight, marital and employment status, length and session of dialysis and smoking. All participants had a spouse and a sexual partner before and after the inception of HD.

The length of HD sessions in all the study patients was approximately 4 h and the frequency of HD was three times a week with close KT/V (K: clearance of dialyzer, T: time of dialysis and V: volume of body fluid), which did not change during the study for all the patients.

We included in the study patients older than 18 years who attended regular HD three sessions per week, received HD ≥3 months, had the level of hemoglobin (Hb) >80 g/L and did not take vitamin C at least from three months before the study. We excluded from the study patients who had active infection or active cancer. Only 57 patients completed the study (30 persons in the intervention and 27 persons in the control group), and [Figure 1] shows the recruitment consort diagram. Sample size was determined by elements such as (1) estimation of outcomes in each group, (2) the α (type I) error level, (3) the statistical power error level and (4) the standard deviation of the measurements for continuous outcomes. In this study, P-values <0.05 were considered as significant, and the statistical power was considered as 80%.
Figure 1: Consort diagram of the study.

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We obtained verbal and written consents from all the study patients after informing each participant about the study purposes, confidentiality of their information and the possibility to withdraw from the study at any stage. Ethical approval was obtained from the institutional ethical committee.

The research instruments used in our study consisted of demographic and MFI-20 and ENRICH questionnaires. These questionnaires were filled at the start and at the end of the study.

The questionnaire of demographic data consisted of age, gender, marital and educational status, number of children, employment status, income, weight, smoking history, causes of kidney disease and vintage of dialysis.

The MFI-20 questionnaire consisting of 20 items (including five sub-scales, and each sub-scale consisted of four items) is a self-report instrument measuring the level of fatigue. It included five dimensions such as general, physical and intellectual fatigue, reduced activity and motivation. Each item was rated over a scale from 1 to 5 and each sub-scale was rated from 4 to 20. The higher score demonstrated a greater level of fatigue. The respondents had to compare each of 20 declarations on how they had been feeling lately. The MFI-20 was extensively used; it discovered a fine internal constancy with an average α-coefficient between 0.65 and 0.89.

We used a sub-scale of the ENRICH questionnaire to evaluate the marital satisfaction in the study patients. We used the PREPARE/ENRICH Inventory (the ENRICH Couple Scales) that included ten items that assessed the marital satisfaction. One of these ten items assessed sexual satisfaction. The total score was the sum of positive and negative items and ranged from 10 to 50. The mean and the scoring levels were based on a national sample of 50,000 married couples with data on ENRICH described in a book by David Olson, Amy Olson-Sigg and Peter Larson. [44] An average Cronbach's α coefficient of 0·80-0.85 and 80-85% discriminant validity in discriminating happy from displeased couples demonstrated that internal consistency and construct validity of the ENRICH questionnaire were acceptable. [45]

Laboratory investigations included serum levels of Hb, hematocrit (Hct) and ferritin, which were measured at the start and at the end of the study. The blood samples were obtained from the venous line at the beginning of the HD sessions.

In the intervention group, 250 mg of vitamin C was injected immediately at the end of each HD session via the intravenous route three times a week for eight consequent weeks; in the control group, placebo saline was injected instead. Although the recommended amount for vitamin C intake in patients on HD is 100-200 mg/ per day, [46] only 250 mg of vitamin C three times a week - lower than the safe dosage recommended by the National Institute of Health (NIH) - was prescribed in order to avoid oxalosis in the study patients.


   Statistical Analysis Top


All data were displayed as mean (SD). The χ2 test, T-test, Paired T-test and ANOVA were used in this study. The data were analyzed via the SPSS software (version 18).


   Results Top


Of the 57 study patients, 35 (61.4%) were males and 22 (38.6%) were females and their mean age was 57.7 ± 11.1 years (range 27-80 years). The mean age of the males (58.05 years) was similar to that of females (57.1 years). Thirty (52.6%) of the patients were retired. The mean age for the retired, unemployed and employed individuals was 59.3, 64 and 47.1 years, respectively. The mean of HD duration was 48.7 ± 60.4 months (range 3-300 months). The prevalent causes of nephropathy included hypertension (HTN) and diabetes (DM); there were 26.3% HTN, 14% DM, 24.6% HTN and DM simultaneously. The educational level of 52.6% of the patients was primary-secondary. The mean of the duration of marriage was 32.4 years and the mean number of children was 3.2. The mean of the marital satisfaction level score before the administration of vitamin C was 36.37. Demographic characteristics of patients are shown in [Table 1] and [Table 2].
Table 1: Baseline qualitative characteristics of the respondents.

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Table 2: Baseline quantitative characteristics of the respondents

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Approximately 30% of the patients complained of marital dissatisfaction, and more than 49% of them had sexual dissatisfaction. Duration of marriage was more than 30 years in 64.9% of the patients. Of the study patients, 15.8% of men and 10.6% of women declared marital dissatisfaction, and 54.4% of men and 33.3% of women stated sexual dissatisfaction.

The mean of fatigue scale was 62.66 ± 15.7. The means of serum Hb, Hct and ferritin were 10.9 ± 1.43 g/dL, 33.9 ± 4.30% and 737 ± 736 ng/mL, respectively.

There was a significant and direct relationship between marital and sexual satisfaction (P = 0.001), which indicated that the increase of sexual satisfaction resulted in an increase of marital satisfaction. Although a one-way ANOVA showed the existence of a positive statistical relationship between age and fatigue score (P = 0.005); there was no meaningful relationship between age and marital (P = 0.31) and sexual satisfaction (P = 0.5). A statistically significant relationship was found between dialysis vintage and fatigue (P = 0.02), but no significant relationship was observed between dialysis vintage and marital (P = 0.43) and sexual satisfaction (P = 0.48). A one-way ANOVA between groups established the existence of a statistical correlation between marital satisfaction with fatigue (P = 0.01). This indicated that marital satisfaction increased whenever the fatigue levels decreased. There was a statistical relationship between serum levels of Hb (P = 0.009) and Hct (P = 0.02) with fatigue, but no significant correlation between these parameters and marital (P = 0.42, 0.45) and sexual satisfaction (P = 0.38, 0.65) was demonstrated. An independent samples t-test yielded no significant relationship between gender with marital satisfaction, sexual satisfaction and fatigue (P = 0.48, 0.64 and 0.51, respectively). There was no significant relationship between marital and sexual satisfaction with the duration of marriage (P = 0.97) and the number of children (P = 0.95). Moreover, we observed no significant relationship between occupation and marital (P = 0.52) and sexual satisfaction (P = 0.85). The highest mean of fatigue was seen in individuals with diabetes. There was no significant correlation between causes of nephropathy and marital satisfaction, sexual satisfaction and fatigue (0.7, 0.6 and 0.59, respectively).

As shown in [Table 3], the intervention group of patients who received supplemental vitamin C attained greater ameliorations in marital satisfaction than the control group. The independent t-test of the difference of the means between the intervention and the control groups indicated that marital satisfaction increased significantly in the intervention group (P = 0.001): Baseline 35.7 ± 5.10 versus a final score of 38.0 ± 5.30 (effect size of marital satisfaction was 0.24 and confidence interval: 34.6-37.8); in contrast, this mean decreased in the control group: Baseline 37.1 ± 7.10 versus a final score of 34.8 ± 7.40.
Table 3: Variable alterations in different stages of the study.

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   Discussion Top


We hypothesized that supplemental vitamin C would have an effect on self-reported marital satisfaction and designed this study to test that hypothesis. The intervention group in our study that received supplemental vitamin C attained greater ameliorations in marital satisfaction than those in the control group; this improvement was not significant. Thus, our study supports the association between vitamin supplementation and an increase in the mean of marital satisfaction.

The comparison between the intervention group and the controls showed the existence of significant changes of the serum levels of Hb and Hct in the intervention group and no significant difference in the serum level of ferritin in both groups. Vitamin C can decrease recombinant human erythropoietin (rHuEpo) resistance in HD patients. It increases the available iron by releasing iron from ferritin and its mobilization from the reticuloendothelial system to transferrin. [47] Furthermore, our study found a statistically significant negative relationship between marital satisfaction and level of fatigue (P = 0.01). Fatigue is one of the most common side-effects of HD and can predict cardiovascular events. It impairs the quality of life in HD patients and causes patients' reluctance to comply with their prescriptions. As others, [28] our study also showed that vitamin C supplementation significantly decreased fatigue complaints in the HD patients.

Our study demonstrated that more than 49% of the study patients had sexual dissatisfaction. Asadifard et al [28] studied 100 women on chronic HD. Results indicated that more than 60% of the patients suffered from a range of sexual dysfunction. Seethala et al [21] also found 80% of women on chronic HD with impaired sexual function.

Bay et al [44] proposed that stretching and breathing exercises resulted in improved sexual satisfaction. Although his study showed that sexual satisfaction improved, it did not sustain significance.

Most of the studies about marital satisfaction in HD patients focused on the relationship between the marital dissatisfaction and the psychological symptoms, such as depression and anxiety; there are a few studies that evaluated the effect of vitamin supplementation on marital satisfaction. HD patients are at risk of low levels of serum vitamin C. [48] According to Dashti, approximately 54% of the patients on HD suffer from vitamin C deficiency. [49]

Vitamin C is a water-soluble vitamin; regular HD can reduce it [50],[51] and dietary restrictions as a result of fear related to hyperkalemia [37] and concerns about inducing oxalosis can result in a significant deficiency of this vitamin. Although the normal range of serum vitamin C is 30-60 μM, the majority of HD patients have serum levels of vitamin C less than 10 μM and even some of them have less than 2 μM. [43] Moreover, chronic inflammation due to the release of inflammatory mediators in the HD patients can reduce the production of essential antioxidants and increase oxidative stress [52] and free radicals. [53] Vitamin C plays a role as an important antioxidant that can decrease the oxidative stress and ameliorate the chronic inflammation.

Even if the intake of 60-100 mg of vitamin C for health maintenance in an individual with normal kidney function is sufficient, it may not be adequate in a HD patient due to the aforementioned reasons. Accordingly, the recommended allowed amounts for the daily intake of vitamin C in HD patients are 100-200 mg that almost none of the HD patients use. [54]

No relationship was observed between weight, age, dialysis vintage, educational level, duration of marriage, age difference of the couples and the number of children and marital satisfaction. Thus, vitamin C supplementation had a tendency of improving the marital satisfaction independent of the education level and age.

The limitations in our study included the inability to measure the plasma levels of vitamin C before and after the study in order to know the patients who had vitamin C deficiency. Another limitation of this study was the small sample size. Performing studies with larger sample sizes and longer-term usage of vitamin C are recommended.

We conclude that marital dissatisfaction is a common disorder in patients on HD that is still significantly understudied. Assessment of marital dissatisfaction in the clinical setting is recommended to identify and monitor couple dissatisfaction and family problems experienced by patients undergoing HB. Standardized assessment of fatigue and anemia are especially recommended to identify those at risk of marital disagreement. Our findings highlighted the importance of focusing on marital satisfaction and indicated that vitamin C supplementation may be a simple and useful intervention in modifying marital dissatisfaction. The results from the study also established a path for further investigation with a larger sample size and longer-term usage of vitamin C.


   Acknowledgment Top


This manuscript was one part of a master degree thesis supported by the Baqiyatallah University of Medical Sciences. This project was supported by a grant from the Nephrology and Urology Research Center of Baqiyatallah University of Medical Sciences. The authors gratefully acknowledge the assistance of all participants and nurses of the Baqiyatallah and Shahid Chamran hospitals.

 
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Correspondence Address:
Dr. Ali Tayebi
Nursing School of Baqiyatallah University of Medical Sciences (Velayat complex), Nobonyad Square, Babayi Highway, Tehran
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DOI: 10.4103/1319-2442.157312

PMID: 26022016

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    Tables

  [Table 1], [Table 2], [Table 3]



 

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    Abstract
   Introduction
    Materials and Me...
   Statistical Analysis
   Discussion
   Results
   Acknowledgment
    References
    Article Figures
    Article Tables
 

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