Chronic kidney disease (CKD) is a common disabling disease with a prevalence of approximately 700 million people worldwide. End-stage kidney disease (ESKD), the last stage of CKD, is an estimated glomerular filtration rate of less than 15 mL per minute per 1.73 m2 body surface area or for those requiring dialysis.

The current management of ESKD is renal replacement therapy, either by dialysis or transplantation. Saving the lives of ESKD patients is very important, and dialysis has succeeded in doing so, but maintaining a high quality of life (QoL) is also essential. Patient’s quality of life may be impacted by hemodialysis due to its chronic nature, frequency, and the fact that most suffer from additional conditions that make them reliant on others.

Quality of life, a general term for well-being, covers many aspects of individual life, including wealth, employment, environment, physical and mental health, and religious beliefs. The concept of health-related quality of life (HRQoL) has been used to correlate a people’s health status to their QoL.

It has been investigated among hemodialysis patients, and some determinants have been proposed, with the majority of scores indicating that it is decreased in these patients.

Demographic characteristics (e.g., age, educational level, income, and sex), and clinical and laboratory characteristics (e.g., number of comorbidities, medications, CKD complications, and haemoglobin < 11) have been found to correlate with HRQoL in hemodialysis patients.

Pain is a common complaint among hemodialysis patients. Recent studies show that about 33%-82% of hemodialysis patients report chronic pain. In contrast, the prevalence of chronic pain in the general adult population with or without kidney problems in the US was 20%. Chronic pain could limit the daily activities of hemodialysis patients and affect their QoL.

Some social, clinical, and laboratory factors have been suggested as chronic pain determinants, including age, educational level, employment, body mass index and comorbidities, haemoglobin, and vitamin D.

Vitamin D is a lipid-soluble vitamin that can be taken from the diet or synthesized in the skin and converted into its active form by a two-step process in the liver 25-hydroxylation and kidney 1-hydroxylation. Vitamin D deficiency, defined as the level of 25-hydroxyvitamin D (< 20 ng/mL), is an emerging worldwide problem in the general population. In particular, ESKD patients are at high risk of vitamin D deficiency, with some studies finding the prevalence was 80%.

Furthermore, the role of vitamin D in chronic pain has been reported in some literature. Again, its relation with QoL has been studied with controversial results; some noted that QoL’s physical and mental components are affected, but others found that only the mental component is affected.