This analysis found that the majority of patients who are deemed suitable to temporarily convert to twice weekly dialysis were able to safely dialyse twice weekly for at least 1 month during the COVID-19 pandemic, enabling safer grouping of patients to reduce potential viral exposure and transmission and ease service demands which may have been exacerbated by staff sickness. However, this was only possible with very close monitoring via dedicated clinician time and through the use of digital technology allowing remote monitoring of biochemistry and dialysis parameters. The necessity for close monitoring can be demonstrated for two reasons. Firstly, longitudinal assessment of dialysis parameters demonstrated statistically significant increases in pre-dialysis systolic blood pressures and pre-dialysis potassium in those patients who continued to receive twice weekly dialysis, although overall these parameters remained well within ‘safe’ limits. Secondly, it was also noted that the rate of patient transfer back to thrice weekly dialysis was constant throughout the project at around 3–4% per week.
Rising SBP despite no significant increase in pre-dialysis weight suggests that blood pressure changes were not necessarily related to increases in extracellular blood volume (ECV). This finding is not surprising given that more frequent dialysis has been shown to improve blood pressure control through various mechanisms. These include reduced ECV, increased sodium removal, reduced sympathetic tone and removal of vasoactive factors which may be driving hypertension [14–16]. There were similar numbers of patients with a pre-dialysis SBP > 180 mmHg before the project commenced compared with at the end of this twice weekly dialysis project (17 versus 20). A value of SBP > 180 mmHg as a trigger for closer dialysis parameter observation and possible conversion back to thrice weekly after the next dialysis session was based upon evidence that this value delineates an increased mortality risk in dialysis patients, although this evidence is conflicting [17].
There was little difference in the UF volumes in the twice weekly patients at baseline compared with those still maintaining on the twice weekly protocol at the end of the 4-week period (1.4 (1.0–2.0) litres per session compared with 1.5 (1.0–2.0) litres per session). However, this excludes the 19 (13.5%) patients who were transferred back to thrice weekly because of fluid-related issues This suggests that residual renal function alongside dietetic salt and fluid restriction advice enabled this population to maintain their target weight.
Due to reduced weekly dialysis time it is unsurprising that the median pre-dialysis potassium significantly increased every week. A pre dialysis potassium > 6.0 mmol/L has been suggested as a threshold whereby mortality risk substantially increases [18]. However only 6 patients had a pre-dialysis potassium above 6.0 mmol/L and 75% of the patients had a pre-dialysis potassium ≤ 5.4 mmol/L at the end of this project. This was the same as in the thrice weekly population. Only 2 of the 6 patients with this degree of hyperkalaemia had previously had a pre-dialysis potassium above 6.0 mmol/L during the entire project. We had made no changes to dialysate potassium concentrations because recent evidence has suggested a higher mortality risk when patients are dialysed against a low potassium dialysate (1mEql/l), particularly those patients with a higher serum potassium [19]. The use of potassium binders, sodium bicarbonate and responsive dietetic consultations mitigated against the need to increase dialysis session frequency in 9 patients. The role of potassium binders to reduce hyperkalaemia events and major adverse cardiovascular events in dialysis patients has not been researched in any randomised control study [12].
There were no significant differences between hospitalisations, COVID-19 infections and deaths between the two groups although the twice weekly group were on average 6 years older than the thrice weekly group, perhaps representing a more at-risk group, although they had lower prevalence of heart failure. There was no evidence that any of the 6 deaths in the twice weekly dialysis group were caused by a reduction in dialysis frequency. There were no hospitalisations for fluid overload in the twice weekly group.
The analysis of this 4-week period of change in dialysis protocol is not intended to re-energise the debate over long-term dialysis frequency and dialysis dose but provides a potential methodology to appropriately and safely rationalise dialysis resources during a health service crisis such as the current pandemic. Although we are not recommending generalisation of our approach as health care management differs markedly throughout the world, it may have implications for other countries where dialysis resources are limited.
At this stage, having passed the first peak of the COVID-19 pandemic in our geographical region, all our in-centre haemodialysis patients are now being individually reassessed for their suitability and preference for either home haemodialysis or peritoneal dialysis, the latter with particular relevance to patients with residual urine output currently treated with twice weekly haemodialysis. Patients who will not be suitable or do not wish to be transferred to home therapies and do not have significant formally quantified residual renal function will return to thrice weekly dialysis in a planned fashion over the next few weeks [20].