Effects of three rehydration methods on prevention of on-site and delayed blood donation-related vasovagal responses: a cluster-randomized trial

Abstract

Objective To compare the effects of 3 rehydration methods before blood donation on the prevention of on-site and delayed blood donation-related vasovagal response (VVR) . Methods From January to June 2021, 6 250 whole blood donors in 6 fixed blood donation sites signed informed consent and were divided into 198 clusters according to donor sites and dates, then they were randomly assigned to receive either oral rehydration salts (ORS), sugar water, or water group, and each drank 500 mL of ORS, sugar water or water within 20 minutes before blood donation. The researchers recorded the actual intervention accepted on site, and recorded the immediate VVR and related information. At rest after blood donation, donors submitted an electronic questionnaire containing socio-demographic information. At 48 hours after blood donation, the researchers called back every donor to record delayed VVR and related information. Logistic regression based on intention to treat (ITT) was used to analyze the difference of the incidence of VVR among the three groups, and the average treatment effect on treated (ATT) was calculated. PASS 2021was used to estimate the sample size and R (4.2.0) for statistical analysis. Results The cumulative incidence of blood donation-related VVR was 2.67% (2.29%-3.11%) among street whole blood donors under the 3 rehydration methods, in which, the incidence of immediate and delayed VVR was 1.02% (0.79%-1.31%) and 1.65% (1.36%-2.01%) respectively. ITT analysis found that ORS were more effective than water in reducing the incidence of delayed VVR【OR=0.59,95% CI[0.37,0.94]】.There was no significant difference in the incidence of immediate VVR between any two groups (P > 0.05), and there was no significant difference in the incidence of delayed VVR in the sugar water group compared with the water group (P > 0.05). There was a difference of -0.013 (【95% CI[-0.022, -0.004]】or -0.008【95% CI[-0.017, -0.000]】in the incidence of delayed VVR in the ORS group compared with water group or sugar water group, the difference was significant (P<0.05). The cumulative VVR of the three groups showed similar results to the delayed VVR. Conclusion Drinking ORS before blood donation is the most effective rehydration method to prevent delayed VVR. The next step is to establish the predictive model of delayed VVR to screen the susceptible population and provide them with ORS before blood donation, while other population can choose any liquid they like, thus achieving personalized blood donation-related VVR prevention and control.

Keywords

• blood donation-related vasovagal responses
• cluster-randomized trial
• logistic regression
• average treatment effect on the treated (att)