Cognitive impairment on haemodialysis: the risk factors worth acting on

Design

Umbrella review and meta-analysis of 5 meta-analyses

Population

Adults on maintenance haemodialysis; 97 associations

Primary outcome

Factors associated with cognitive impairment and cognitive frailty

Effect

Cognitive frailty: depression OR 4.66, low-flux dialysis OR 4.16, intradialytic hypotension OR 2.42

This umbrella review pooled five meta-analyses covering 97 associations with cognitive impairment, or with cognitive frailty, in adults on maintenance haemodialysis.

Cognitive impairment was associated with older age, female sex, diabetes, cerebrovascular disease, multiple comorbidities, poorer physical performance, lower haemoglobin and inflammatory markers; higher education was protective (odds ratio 0.21). Cognitive frailty was associated with depression (4.66), previous stroke (2.94), malnutrition, longer time on dialysis (2.30), low-flux dialysis (4.16) and intradialytic hypotension (2.42), with albumin protective. Only two associations reached moderate certainty.

Several of these are things a dialysis unit can change or screen for: anaemia, depression, nutrition, dialysis membrane and blood pressure falls on dialysis. Cognitive impairment affects adherence, fluid control and consent, so it is worth identifying. These are associations, not proof that correcting them protects cognition.

• Screen for cognitive impairment periodically in older haemodialysis patients.
• Screen for depression, which was strongly associated with cognitive frailty.
• Work to limit intradialytic hypotension.
• Review anaemia and nutritional status as part of cognitive risk.
• Consider high-flux membranes where available.

Why it matters

Unrecognised cognitive impairment undermines fluid restriction, medication use and informed consent on dialysis.

Don't overread it

Mostly low-certainty associations; it does not show that treating these factors protects cognition.

The statistics, in plain English

An umbrella review summarises existing meta-analyses rather than original studies. Odds ratios of 2 to 5 suggest strong associations, but most were rated low or very low certainty, and observational designs cannot show that correcting a factor improves cognition.

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