Heparin versus citrate anticoagulation for continuous renal replacement therapy in intensive care: the RRAM observational study.

BACKGROUND

In the UK, 10% of admissions to intensive care units receive continuous renal replacement therapy with regional citrate anticoagulation replacing systemic heparin anticoagulation over the last decade. Regional citrate anticoagulation is now used in > 50% of intensive care units, despite little evidence of safety or effectiveness.

AIM

The aim of the Renal Replacement Anticoagulant Management study was to evaluate the clinical and health economic impacts of intensive care units moving from systemic heparin anticoagulation to regional citrate anticoagulation for continuous renal replacement therapy.

DESIGN

This was an observational comparative effectiveness study.

SETTING

The setting was NHS adult general intensive care units in England and Wales.

PARTICIPANTS

Participants were adults receiving continuous renal replacement therapy in an intensive care unit participating in the Intensive Care National Audit & Research Centre Case Mix Programme national clinical audit between 1 April 2009 and 31 March 2017.

INTERVENTIONS

Exposure - continuous renal replacement therapy in an intensive care unit after completion of transition to regional citrate anticoagulation. Comparator - continuous renal replacement therapy in an intensive care unit before starting transition to regional citrate anticoagulation or had not transitioned.

OUTCOME MEASURES

Primary effectiveness - all-cause mortality at 90 days. Primary economic - incremental net monetary benefit at 1 year. Secondary outcomes - mortality at hospital discharge, 30 days and 1 year; days of renal, cardiovascular and advanced respiratory support in intensive care unit; length of stay in intensive care unit and hospital; bleeding and thromboembolic events; prevalence of end-stage renal disease at 1 year; and estimated lifetime incremental net monetary benefit.

DATA SOURCES

Individual patient data from the Intensive Care National Audit & Research Centre Case Mix Programme were linked with the UK Renal Registry, Hospital Episode Statistics (for England), Patient Episodes Data for Wales and Civil Registrations (Deaths) data sets, and combined with identified periods of systemic heparin anticoagulation and regional citrate anticoagulation (survey of intensive care units). Staff time and consumables were obtained from micro-costing. Continuous renal replacement therapy system failures were estimated from the Post-Intensive Care Risk-adjusted Alerting and Monitoring data set. EuroQol-3 Dimensions, three-level version, health-related quality of life was obtained from the Intensive Care Outcomes Network study.

RESULTS

Out of the 188 (94.9%) units that responded to the survey, 182 (96.8%) use continuous renal replacement therapy. After linkage, data were available from 69,001 patients across 181 intensive care units (60,416 during periods of systemic heparin anticoagulation use and 8585 during regional citrate anticoagulation use). The change to regional citrate anticoagulation was not associated with a step change in 90-day mortality (odds ratio 0.98, 95% confidence interval 0.89 to 1.08). Secondary outcomes showed step increases in days of renal support (difference in means 0.53 days, 95% confidence interval 0.28 to 0.79 days), advanced cardiovascular support (difference in means 0.23 days, 95% confidence interval 0.09 to 0.38 days) and advanced respiratory support (difference in means, 0.53 days, 95% CI 0.03 to 1.03 days) with a trend toward fewer bleeding episodes (odds ratio 0.90, 95% confidence interval 0.76 to 1.06) with transition to regional citrate anticoagulation. The micro-costing study indicated that regional citrate anticoagulation was more expensive and was associated with an estimated incremental net monetary loss (step change) of -£2376 (95% confidence interval -£3841 to -£911). The estimated likelihood of cost-effectiveness at 1 year was less than 0.1%.

LIMITATIONS

Lack of patient-level treatment data means that the results represent average effects of changing to regional citrate anticoagulation in intensive care units. Administrative data are subject to variation in data quality over time, which may contribute to observed trends.

CONCLUSIONS

The introduction of regional citrate anticoagulation has not improved outcomes for patients and is likely to have substantially increased costs. This study demonstrates the feasibility of evaluating effects of changes in practice using routinely collected data.

FUTURE WORK

(1) Prioritise other changes in clinical practice for evaluation and (2) methodological research to understand potential implications of trends in data quality.

TRIAL REGISTRATION

This trial is registered as ClinicalTrials.gov NCT03545750.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in

Acute kidney injury, which prevents kidneys from working properly, is common in critically ill patients being treated in an intensive care unit. Patients with acute kidney injury are treated with a machine that takes over kidney functions, a process called continuous renal replacement therapy. Traditionally, as part of continuous renal replacement therapy, heparin (an anticoagulant that stops the blood from clotting) is added to the blood as it enters the continuous renal replacement therapy machine. Recently, citrate anticoagulation (an alternative to heparin) has been increasingly used in intensive care units in the UK. However, the increased use of citrate is happening without evidence that this is better for patients and cost-effective for the NHS. We aimed to find out whether or not changing to citrate anticoagulation for continuous renal replacement therapy is more beneficial than heparin anticoagulation for patients with acute kidney injury treated in an intensive care unit. We also looked at whether or not changing to citrate is cost-effective for the NHS. We used routinely collected data from the Intensive Care National Audit & Research Centre Case Mix Programme national clinical audit to identify 69,001 patients who received continuous renal replacement therapy in an intensive care unit in England or Wales between 1 April 2009 and 31 March 2017. To get a more comprehensive view of the long-term effects of changing to citrate, we ‘linked’ data from the 69,001 patients together with other routinely collected data sets to get information on their hospital admissions, longer-term kidney problems and survival after leaving the intensive care unit. We combined this information with a survey of anticoagulant use in intensive care units in England and Wales to compare patients who received continuous renal replacement therapy with heparin and citrate. We found that the change to citrate was not associated with a significant change in the death rate at 90 days, but that it was more expensive for hospitals. Our findings suggest that the change to citrate-based anticoagulation may have been premature and should cause clinicians in intensive care units that are still using systemic heparin anticoagulation to pause before making this change.