[Evaluation of measurements intended to develop regularity of blood donation].

An increase in the regularity of blood donation is desirable for two main reasons. First, the lower incidence of viral disease markers in regular donors when compared to first donors could help to reduce risks of transmissible diseases. Second, a higher frequency of donation could contribute to a more satisfactory supply of blood products. Two measures implemented with the aim of increasing the regularity of blood donation were evaluated: (i) an increase in the annual frequency of blood collection by mobile teams at collection sites, and (ii) a "next donation document" given to each donor indicating the earliest possible date of the next donation. The regularity index was calculated as the mean number of cellular donations (whole blood and platelet apheresis) per donor per year, over two consecutive periods: 1-7-1993-30-6-1994 (P1) and 1-7-1994-30-6-1995 (P2). The junction of these two periods corresponded to the date of introduction of the "next donation document" and to the time of reinforcement of the mobile collection frequency. First donors in either period were not taken into account in the study. A significant relationship was observed between the annual frequency of mobile collection and the average number of donations per donor (comparison test of two means on large samples, p < 0.001 in all the cases excepted those of stable mobile collection numbers). Thus, in the first period, the average donation rate was the lowest on sites having only one mobile collection per year (M: 1.55, W: 1.38) and the highest on sites with five mobile collections per year (M: 2.05, W: 1.71). These average numbers significantly increased in the second period as compared to the first (M: +4.8%, W: +1.8%; comparison test of two means from paired series, p < 0.001), as did the yearly frequency of mobile blood collections (+9.2%). On the other hand, the "next donation document" was not associated to any change in the regularity index. The results of this study therefore showed an increase in the frequency of visits of mobile collection teams to be the main factor leading to an improvement in the regularity of blood donation. Moreover, this evolution was associated with a decrease in the incidence of viral markers detected at donation.