Further developments of Model II

such dietary prescriptions. All the patients were on a mixed diet combining animal and plant sources of food.

5:4. PATIENTS’ ANTHROPOMETRIC MEASURES.

The heights of the patients were comparable across all the stages of CKD.

There was an observable progressive decrease in the mean weights of patients with advancing stage of CKD. There was also a progressive decrease in mean BMI from stages 2-4 with a slight increase in stage 5. The possible explanation for the higher mean BMI for patients in stage 5 may be from clinically undetectable fluid retention in this stage of the disease. Fluid retention in advanced stages of CKD has been shown to be associated with mortality in this category of patients.¹⁴⁹

Tayyern et al¹⁵² found an inverse relationship between age and SGA scores thus refuting the association of worse nutritional status with age. The findings of Morais and others associating poor nutritional state with aging may be attributable to prolonged duration of illness, complications of illness or effect of long dependence on dialysis. The older an individual grows the longer he may have had his illness or been on dialysis. In this study, clinical assessment and TSF showed a significant relationship between malnutrition and the age groups. This finding was not consistent throughout the study where other tools for assessment were used. It may be argued that this finding with TSF may have resulted from changes in the structure and thickness of the skin. This has been reported as part of the normal physiological processes associated with the process of aging.¹⁵⁰ This has been attributed to either a reduction in the collagen synthesis or a loss of the normal integrity of the collagen synthesized. There is also a gradual decrease in the underlying fat and subcutaneous tissue. However, Kapoor et al¹⁵³ in a study in India reported that TSF was not only a good tool for nutritional assessment and identification of subclinical malnutrition but a good tool at determining adverse outcomes in adults with CKD. It is possible therefore, that the association of malnutrition with aging by TSF is from poor nutritional state or a loss of skin integrity or both. In this study there was a progressive increase in the BMI and weak but not significant association with advancing age. Other studies have shown that body weight and body mass index (BMI) increase with age until approximately 50 to 60 years, after which they decline. ¹⁵³ The proportion of patients malnourished

when assessed by BMI was not increased with advancing age probably due to this gradual increase with age of BMI. The higher BMI with age may afford older patients higher BMI scores thereby falling within range of normal. With age too, the spine is believed to be shorter, heights lower and BMI higher for older patients. This study also had a very high proportion of young respondents, and only 11.8% of respondents above 60 with the eldest participant being 72 years old. Perhaps, the tools used for this study are not the optimum for assessing malnutrition in the elderly. The national Institute of Clinical Excellence (NICE), the British Association for Parental and Enteral and Nutrition (BAPEN) and the British Dietician Association (BDA) all recommend the use of the Malnutrition Universal Screening Tool (MUST) for elderly patient in the hospital and community.^154-156

The various tools used did not consistently show which of the sexes was at a greater risk of malnutrition. Various studies have also had conflicting reports with respect to which of the sexes presented more with malnutrition.

Reports from community studies tend to suggest that females were more at risk of malnutrition than males. In this study the various tools used identified one of either sex as having a higher proportion of malnutrition. In this study, the females had a higher mean BMI, mean upper arm fat areas but the males had a higher upper arm muscle area. These differences are believed to be mediated by several factors including hormonal difference.

More males were affected in this study with malnutrition as assessed by BMI and MUAC. The proportion of both sexes having low cholesterol levels was equal. A greater proportion of females were malnourished when

assessed with the use of TSF, serum albumin, clinical assessment, SGA and ISRNM criteria. In their study Marcén et al¹⁵⁷ found a higher prevalence of malnutrition among males. The prevalence of moderate/severe malnutrition in their study was 51.6% among men and 46.3% among women. In another study using SGA, Espahbodi et al¹⁵⁸ found all the patients having severe malnutrition to be males in their study. CKD is generally believed to progress faster in males than females. Whether this translates to more prevalence of malnutrition is not clear. Factors that may contribute to malnutrition include anorexia leading to poor nutritional state among other factors. In this study and several other studies a number of patients had anorexia. Carrero et al ¹⁶⁶ had shown that men who were uraemic were more susceptible to anorexia. This may put them at greater risk of malnutrition induced by uraemia. Other studied found a greater proportion of females having malnutrition. In a study in Iran, Farrokhi et al¹⁵⁹ showed that malnutrition was significantly more frequent in females. The mechanism of the gender discrepancy in factors related to nutritional deterioration is complex and poorly understood. Women in general have been reported to be in a greater risk of malnutrition than men due to several factors such as their reproductive biology, low social economic status and a general lack of education. Stunting has also been reported to be more in women.¹⁶⁰ The gender may actually have little or no role in determining the risk of malnutrition.

Socioeconomic status (SES) has been recognized as one of the key factors impacting on disease outcome. Some authors argue that low social class

does not lead to increased mortality. Fancourt et al¹⁶¹studied the phenomenon of increased mortality in the lower social class and found no association between inadequate nutrition and mortality. They argued that people in the different social class may have differing choices in terms of quality of food but malnutrition was not a function of social class in adults.

This view is however not shared by other authors. People of low SES are believed to have higher risk for mortality and morbidity compared to those of higher SES.¹⁶² Bello et al¹⁶³ have established a direct link between a low SES and the severity of CKD. They observed that people of low SES presented to hospital with low GFR. In this study the majority of the patients were in the lower social class. Though there was no significant relationship between the social classes and malnutrition, the fact that most of the patients are of a lower SES suggests that they may have greater morbidity from CKD. The ARIC study further underlined the place of SES in the presentation and outcome in CKD. Part of the conclusion drawn from the study was that the previously established disparity in severity of CKD between blacks and white was due mainly to difference in SES.¹⁶⁴ Blacks in the lower socioeconomic class have a higher and a more severe form of CKD.

In this present study, part of the observation was that one of the key factors determining the presence of malnutrition was the severity of CKD. If more patients are in the lower social class which has been established to account for more severe CKD, it is possible therefore to reason that malnutrition will be more frequent in them and in a more severe form. Majority of the patients in this study were of the lower social economic. People of this class are more

likely to consume diets that are not balanced with low intake of vitamin containing fruits and vegetables. As a result, micronutrient deficiency will result, leading to a low resistance to infections. It may not be possible to initiate a social migration for these patients but adequate dietary counselling can help them channel scarce resources more appropriately.

5:5.1 THE PATTERN/ PREVALENCE OF MALNUTRITION.

There was an increase in the proportion of CKD patients malnourished by use of BMI across the stages of CKD with advancement in renal failure. The pattern was however not maintained for stage five of CKD where the proportion of malnourished patients was less than that of stage 4. The BMI of patients is affected by some factors such as fluid retention. Despite the correction for retained fluid in the measurement of weights, retention of fluid in CKD patients may not become clinically detected in the early stages.

Stage 5 represents the stage of CKD with the highest likelihood for fluid retention. The use of BMI for this category of patients becomes less reliable for the assessment of nutritional status since it cannot differentiate between muscle mass, fat mass or fluid retention. The number of normal control with a BMI of <23kg/m² was 7.8%. A BMI of <23kg/m² may overestimate malnutrition in our general population. This may so considering the mean BMI was found among Nigerians to be 23.45±3.89kg/m².^,165,166 The WHO recommends¹⁰¹ the use of a BMI of <18.5kg/m for the general population but this value was found not to be very appropriate for CKD patients because of increased mortality found to be associated with BMI of

<20kg/m². There was a high number of patients (31.4%) found to be

malnourished when the ISRNM recommended cut off point of <23kg/m² was used. This cut is higher than has previously been used in many studies. The proportion of patients with BMI <20kg/m² was 10.7% in this study was comparable to a prevalence of 12.8% in the work by Mancini et al.¹⁶⁷ Beddhu et al¹⁶⁸ recorded similar but lower prevalence of 7.98%. Liman et al¹³⁸ and Agaba et al⁴⁷ had a slightly higher prevalence of 17.7% and 21.6%

respectively using BMI as a tool. These other studies were done in patients with more advanced CKD with mean GFR much lower than the ones in this study. The proportion of patients found to be malnourished would depend on the cut-off point employed in the study. The use of BMI poses a challenge because of the fact that it is not only accounted for by body fat or muscle. In a study employing the ISRNM, the addition of body fat as a percentage of weight was done by some researchers in order to overcome this challenge.¹⁶⁹ Body mass index has a relationship with CKD in a two way fashion. Higher BMI has been shown to be associated with CKD in men especially in Asians.¹⁷⁰ Whether the predominantly low BMI would offer protection to our category of CKD patients is yet to be determined more so, when a large number of CKD in our environment result from post infectious aetiology. On the other hand a lower BMI especially when combined with low serum albumin has been associated with CKD progression and mortality.¹⁷¹ In this study a large proportion of predialytic patients are at a low BMI level. This may mean a more rapid progression of CKD especially with the presence of malnutrition or other markers of malnutrition such as a low serum albumin.

In this study the proportion of patients with serum albumin <38g/L was

higher and comparable with that of BMI and majority had both low BMI and low serum albumin and met the ISRNM criteria for malnutrition. The potential outcome of this combination is a possible worse CKD outcome. A proper point of intervention here would be the correction of serum albumin levels which is easily achievable. This will eventually improve the lean body mass of the patients and improve the muscle fat ratio. However, these values as cut off points for albumin and BMI have not been validated in our population. The cut of < 23 kg/m² may need to be adjusted for our population since it was obtained from an American population by the ISRNM. Notably the highest proportion of patients in this study (48%) had a BMI of between 18.5-24.99. The inappropriateness of this cut off for certain population groups was noted by Japanese researchers when 78% of the patients in their study had BMI <23kg/m². There may be need therefore to make an adjustment to this.¹⁷²

Skin fold thickness serves as a measure of the body fat. The mean TSF for patients in this study was higher for females than males. This difference in the skin fold thickness between males and females, have be ascribed to a difference in the compressibility of skin folds between males and females.

The skin folds of women have been shown to be less compressible than those of men. Factors contributing to this may include differences in the distribution of fibrous tissues and blood vessels in the subcutaneous tissue mediated through perhaps genetic or hormonal difference between males and females.^173,174

The prevalence of malnutrition in this study using TSF was 46.6% in the patient population and 14.7% in the controls. This is the highest prevalence in the study for both patients and control. A similarly high prevalence of malnutrition using TSF was found in the work by Marcen et al¹⁵⁷ with a prevalence in their work using TSF being 41%. Valenzuela et al ¹³⁷ recorded a prevalence of 44.8% using TSF. The use of TSF identifies apparently healthy patients and control as being malnourished. The reference values used for this study and several other studies done in African and outside the United States make use of the NHANES as reference for cut off values. Even when the reference points for blacks are used, there may still be a difference in the body compositions of the blacks in the United States and those that are resident in Africa from environment and social economic influences.

Therefore, the use of TSF, with reference values obtained from foreign subjects, may not be a reliable tool for nutritional assessment and if used alone may lead to erroneous conclusions. It will be better to use it in conjunction with other tools for nutritional assessment. The TSF showed a significant difference with respect to age grades. There was an increase in the proportion of malnourished patients with advancing age. The proportion of patients who were malnourished using TSF varied significantly with the age group. As noted previously, this association may have been influenced by the effect of the aging process on the integrity of the skin. The alteration in the structure and integrity of the skin occurs as the normal physiologic process of aging.

The use of MUAC is a cheap and reliable tool for nutritional assessment. It reflects the nutritional status of adults and has been found to be useful in many settings. It has also been proven to correlate well with BMI in identifying malnutrition in the general population. In this study, a high number, 30.4% of the patients and 11.8% of the controls were found to be malnourished. This is comparable to a prevalence of 34.4% as obtained by Liman et al¹³⁸ in predialytic CKD patients. Other studies had even higher prevalence of malnutrition in CKD patients.^131,136Again, this high prevalence may be due to the fact that the cut-off used were obtained from values from the NHANES III data as reference point. The values of the MUAC obtained, when combined with the TSF has been used to estimate the body fat percentage and can give reliable information about the arm muscle which is a direct reflection of the total lean muscle mass. Other scientific methods such as BIA and DEXA may give more accurate and reliable results but their prohibitive cost makes them unsuitable for routine screening of patients.

Considering the fact that regular screening and follow of CKD patients is being advocated, a simple tool such as the measurement of the MUAC becomes more dependable. It has no risk of radiation exposure and needs little training to carry out.

Serum albumin is perhaps the most frequently used biochemical index both for assessing visceral proteins and malnutrition. Biochemical assessment of the patients using the serum albumin showed that 26.5% of the patients and 0.9% of the control had hypoalbuminaemia. The number of patients with serum albumin levels <30g/L is comparable to the finding in of Liman

et al¹³⁸ with a prevalence of prevalence of 24.2% of hypoalbuminaemia in their study. Much lower than that obtained by Agaba et al⁴⁷ with a prevalence of 43.2%. This study showed that the more advanced cases of CKD had a greater level of hypoalbuminaemia reaching as much as 50% in stage 5 of CKD. Therefore a higher proportion of patients with hypoalbuminaemia is expected from a study like that of Agaba et al which focused on patients with more advanced CKD. A higher proportion of 46.1%

had hypoalbuminaemia using the ISRNM criteria and a cut of <38g/L was obtained in this study. This proportion is much higher than previous reports from this our environment because of the higher cut off. However, there was no significant relationship between serum albumin levels and age, sex or social class. There was a statistically significant difference in the mean values of albumin among the stages of CKD. The mean serum albumin in stage 2 was lower than stage 3. The possible explanation for this is that the patients in stage 2 were patients with GFR > 60mls/min/1.73m² but with significant proteinuria as one of the main reason for their inclusion in the study. Proteinuria served as a marker of kidney damage in this group for some of the patients. A major drawback of albumin as a marker of nutritional status in CKD patients is the effect of inflammation on its levels.^82,83,84 In this study and in many studies there was a negative correlation between albumin and CRP^82-84,172. This may also account for the progressive decrease in its levels with more advanced CKD which has been shown to be associated with higher levels of inflammation.

Serum cholesterol is a lipoprotein which functions as a precursor for the synthesis of steroid hormones, bile acids and vitamin D. Serum cholesterol and other lipids are indicators of patients’ nutritional status. In this study a total of 11.8% of the patients had hypocholesterolaemia, with levels of cholesterol <100mg/dl while 3.9% of the controls had low cholesterol levels.

Jia Wang ¹⁷⁵in her study found that total cholesterol had a positive correlation with serum albumin and BMI. Also in the same study total cholesterol could predict the SGA and had a higher influence on SGA than albumin. As in this study there was no correlation between the age of the patient and total cholesterol. High levels of cholesterol predispose to cardiovascular disease. Emphasis has largely been focused on the reduction and control of high cholesterol because of its predisposing effect on the cardiovascular adverse events. Similar emphasis is needed with respect to low cholesterol levels in CKD patients especially if they are about to commence dialysis. This is because the outcome for CKD patients with low cholesterol is poor. Some workers are of the view that high cholesterol levels may be associated with better survival in CKD patients who are on dialysis unlike in the general population. This survival advantage is offered mainly to patients who are malnourished or having a high level of inflammation.

Therefore patients with malnutrition with low levels of serum cholesterol stand to benefit from a concerted nutritional intervention aimed at up regulating the level of serum cholesterol. The derivable benefit for predialytic patient is yet to be fully explored. In this study there was a positive correlation though not significant between the level of cholesterol and renal