OBJECTIVE To review all available original publications on the harms and benefits of subcutaneous (SC) hydration in older patients. DESIGN Systematic review and meta‐analysis. PARTICIPANTS All studies on SC hydration in older patients without restrictions on design or language. MEASUREMENTS The Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and Web of Science databases and trial registries were searched from inception to November 5, 2019, and two reviewers independently extracted the data and assessed the risk of bias of individual outcomes. RESULTS Thirty‐one publications from 29 studies met the eligibility criteria. The data from six randomized controlled trials were used for the meta‐analyses. The subgroup analysis including only the studies with the lowest risk of bias showed that SC hydration was associated with fewer adverse effects than intravenous (IV) hydration (risk ratio (RR) = 0.69; 95% confidence interval (CI) = 0.53–0.88; P = .003; n = 4; I2 = 0.0%; 545 infusions in each group). In absolute numbers, patients treated with SC hydration had an incidence rate of 90 adverse effects per 1,000 infusions versus 130 adverse effects per 1,000 infusions (95% CI = 102–169) with IV hydration. Secondary outcomes comparing IV with SC hydration showed that SC was 3.2 minutes faster to set up and markedly reduced the risk of agitation (RR = 0.42; 95% CI = 0.22–0.79; P = .007; I2 = 65%; n = 3); however, SC hydration delivered a lower volume of fluid and was less efficient at reducing serum osmolality (s‐osmolality). CONCLUSIONS SC hydration is safer than IV hydration and potentially reduces the risk of agitation, but it is less effective. SC hydration should be available as an alternative to IV hydration when treating older patients for mild‐to‐moderate dehydration. More high‐quality studies are needed in the field to increase the confidence in the estimates.

Background Hydration therapy is essential in the care of the older patient. Subcutaneous (SC) hydration is a relevant method for parenteral hydration, but clinical trials on the subject have methodological shortcomings compared to updated standards. Design Assessor-blinded, non-inferiority RCT to explore if SC is a safe alternative to intravenous (IV) hydration. Participants Eligible patients were: Admitted patients 65 years or older with a need for parenteral hydration. The targeted sample size was 67 patients in each group. Intervention Patients were randomised to parenteral hydration via an IV or SC catheter during a 24 hours observation period. The non-randomised catheter (inactive) was placed as a sham on the patient, thereby blinding the caregivers and outcome assessors. Measurement Our primary outcome was the proportion of patients reporting at least one adverse effect with a non-inferiority calculation using a 20% margin. Results We included 51 patients, with 24 randomised to SC and 27 to IV. We were unable to reach our target sample size due to challenges in recruitment, time limitation, and COVID-19. For the outcome of adverse effects, SC was non-inferior to IV (p = 0.012). Time spent on inserting the catheters was shorter with SC (p = 0.001). The groups did not differ by pain of insertion, discomfort during infusion, or the risk of developing delirium. Conclusion SC is a safe alternative to IV hydration, is faster to place and should be an available method for parenteral hydration wherever older adults are cared for. Trial registration ClinicalTrials.gov Identifier: NCT03710408

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