Prevalence of Pica in Patients on Dialysis and Associated Nutritional Status Examined

Pica is defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM) as the “intake of a substance or object without calories or nutritional properties at least once a month. Such an intake (including intake of ice, starch, soil, clay, grass, paper, or cigarettes) must not have been initiated in childhood, in the last year, or be a cultural/community habit.”

There are few studies on the epidemiology of pica in patients with end-stage renal disease (ESRD) receiving hemodialysis or peritoneal dialysis; nearly all available data are from case reports, and there are no data available in kidney transplant recipients. Pica may be stimulated by the emotional stress associated with ESRD and ingested substances by patients with pica may contribute to alterations in diet, nutritional status, and micronutrient balance. Further, complications associated with pica, such as anemia, electrolyte alterations, micronutrient and macronutrient malabsorption, and malnutrition, may be exacerbated in ESRD.

Claudia N. Orozco-González, LN, PhD, and colleagues conducted a cross-sectional study designed to examine the prevalence of pica and its association with nutritional status in patients with ESRD receiving chronic dialysis. Results of the study were reported in the Journal of Renal Nutrition [2019;29(2):143-148].

The study was conducted in a tertiary care teaching hospital and included 400 patients on dialysis. Pica, according to the DMS, Fifth Edition, was classified based on type of ingested substances as no pica, ice pica, or hard pica (starch, soil, clay, grass, paper, or other pica). Inclusion criteria were no previous pica diagnosis, transplant, pregnancy, mental illness, or infection. All eligible patients were in the living donor kidney transplant program, had been on hemodialysis or peritoneal dialysis for at least 6 months, were >18 years of age, with any cause of kidney disease, and had provided their oral informed consent.

Mean age of the cohort was 28 years, 70% (n=280) were men, and 76% had an unknown cause of kidney disease. There were no significant differences between patients on hemodialysis and those on peritoneal dialysis; statistical analysis was conducted using data from both types of dialysis combined.

The prevalence of pica in the cohort was 42% (95% confidence interval, 37%-47%). Among those with pica, 46% had ice pica, 29% ate soil, 14% ate two substances, 5% red brick, 3% paper, 2% soap, and 1% cattle pasture. In the group with pica (particularly hard pica), patients were younger, and the proportion of men tended to be lower. They also had lower level of education and a longer duration on dialysis. There were no observed differences based on ESRD etiology or type of dialysis.

Results of analysis of biochemical variables demonstrated the variables were within the range usually seen in this patient population. The only statistically significant between-group differences seen were a higher level of C-reactive protein (CRP) in ice pica patients and lower sodium levels in hard pica patients compared with the other groups. In all groups, mean value of sodium was within normal range (137-145 mEq/L); median CRP was slightly above normal (0-3.0 mg/L) only in the ice pica group.

In results of nutritional evaluation, patients with hard pica had the lowest weight. Three-quarters or less of patients in all groups achieved the calories and macronutrients recommended for this patient population, a finding that was more evident in those with pica.

In the total cohort, according to the DMS, malnutrition, classified as mild-moderate,  was present in 74% of patients. There was an association between the presence of pica and poorer nutritional status; the presence of malnutrition was 67% in patients with no pica, 80% in ice pica, and 89% in hard pica (P=.004). In patients with pica of two substances, the prevalence of malnutrition was 88%, compared with those with hard pica.

When evaluated by means of the DMS, higher CRP, and lower educational level, the worse nutritional status significantly and independently predicted both ice and hard pica. Only hard pica was significantly predicted by lower serum sodium, longer duration of dialysis, and younger age. Dialysis modality did not predict any type of pica.

There were some limitations to the analyses, such as including patients on protocol for living donor transplantation, potentially limiting the generalizability of the findings; the cross-sectional design of the study limiting the ability to establish causality between pica and decreased nutritional status; and not measuring serum levels of oligoelements that have been associated with pica in previous studies.

The authors said, “Pica is highly prevalent in dialysis patients. To the best of our knowledge, the present study is the first study reporting that pica is associated with worse nutritional status in ESRD patients on dialysis and will provide useful information for further investigation.

“Nephrologists and nutrition specialists have to be aware about the relevance and magnitude of the presence of pica in patients on dialysis to intentionally diagnose the problem. Future studies of interventions to reduce pica prevalence and examine the effect on nutritional status are recommended.”

Takeaway Points

  1. Researchers conducted a cross-sectional study to examine the prevalence of pica in patients receiving dialysis; they also investigated the association of pica with nutritional status.
  2. In the cohort of 400 patients with end-stage renal disease on chronic dialysis (hemodialysis or peritoneal dialysis) , the prevalence of pica was 42%.
  3. In multivariate analyses, malnutrition, C-reactive protein, and lower educational level significantly and independently predicted both ice and hard pica.