***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Health tests are often seen as promising donor incentives to improve the supply of blood . However , systematic behavioral evidence on donor recruitment is scarce . STUDY DESIGN AND METHODS To study the effectiveness of a free cholesterol test in attracting  new donors  and motivating previous donors , two field experiments were conducted . In Study 1 , 2825 nondonors were r and omly assigned to one of three treatments : a solicitation letter , a solicitation letter plus an appeal , or a solicitation letter plus an appeal and the offer of a free cholesterol test . In Study 2 , 8269 previous donors were r and omly assigned to one of three treatments : a st and ard invitation , an invitation plus an appeal , or an invitation plus an appeal and a cholesterol test .  Marginal effects from probit estimations were calculated to study the effects of the treatments on donors ' response . RESULTS In Study 1 , only 0.6 percent reacted to the solicitation letter . There were no significant differences in the response rates between the three treatments . In Study 2 , 45.3 percent of the invited previous donors came to donate . The appeal ( marginal effect , -0.5 % ; st and ard error [ SE ] , 1.9 % ) and offering a cholesterol test ( marginal effect , 1.6 % ; SE , 1.8 % ) did not significantly increase the probability of a donation relative to the st and ard invitation . The treatment effects for the cholesterol test did not systematic ally differ between frequent and infrequent donors and female and male donors . There is some evidence that  young donors responded relatively most positive to the cholesterol test ( marginal effect , 4.4 % ; SE , 2.2 % ) . CONCLUSIONS Contrary to conclusions from survey studies , free cholesterol testing did not significantly increase donations from nondonors and previous donors during a 3-month campaign . The two studies show that field experiments are an important method to evaluate donation incentives , because measuring donors ' intentions alone can lead to significantly different conclusions BACKGROUND Some blood donation-related adverse events ( AEs ) can negatively impact the blood donor return rate ( BDRR ) and decrease donor retention . STUDY DESIGN AND METHODS One-thous and r and omly selected whole-blood donors were interviewed 3 weeks after a 525-mL index whole-blood donation for seven AEs . The number of return visits and duration of follow-up were recorded for each of the 1000 donors . A negative binomial regression analysis was used to determine the contribution of the four most common AEs to the BDRR , and interactions between these AEs were also evaluated . RESULTS The four most common AEs were bruise alone ( 15.1 % ) , sore arm " alone " ( 7.0 % ) , fatigue " alone " ( 5.1 % ) , and donor reaction " alone " ( 4.2 % ) , where " alone " is defined to also include donors who had a bruise but no other AE . The estimated BDRR for donations without AEs was 1.32 visits per year . The estimated BDRRs for the four most common AEs were : bruise alone , 1.32 visits per year ; sore arm alone , 1.30 visits per year ( 2 % reduction in BDRR ) ; fatigue alone , 1.06 visits per year ( 20 % reduction in BDRR ) ; and donor reaction alone , 0.87 visits per year ( 34 % reduction in BDRR ) . The BDRR for donor reaction , fatigue , and sore arm together was 0.20 visits per year ( 85 % reduction in BDRR ) . CONCLUSION Donor reaction had the most negative impact on the BDRR . There appears to be a synergistic effect between donor reaction , fatigue , and sore arm . Theoretically , amelioration of some AEs has the potential to improve BDRRs BACKGROUND There are no reports in the transfusion medicine literature that describe adverse reactions and donor arm injuries after whole-blood donation based on solicited information . STUDY DESIGN AND METHODS The present study solicited adverse reaction and donor arm injury information from 1000 r and omly selected whole-blood donors approximately 3 weeks after the whole-blood donation .  Two 16-gauge phlebotomy needles in use were also compared . RESULTS Thirty-six percent of the donors had one or more adverse effects ( AEs ) . The most common systemic AEs were fatigue ( 7.8 % ) , vasovagal symptoms ( 5.3 % ) , and nausea and vomiting ( 1.1 % ) . The most common arm findings were bruise ( 22.7 % ) , arm soreness ( 10.0 % ) , and hematoma ( 1.7 % ) . Men were half as likely as women to have an AE ( 23 % AE vs. 48 % AE , p < 0.0001 ) . Repeat blood donors had fewer AEs than first-time blood donors ( 36 % AE vs. 47 % AE , p < 0.007 ) , and African-American donors had numbers of AEs similar to those of Caucasian donors ( 31 % AE vs. 38 % AE , p = 0.30 ) . The two phlebotomy needles did not differ in causing blood donor AEs . CONCLUSION AEs after donation and complaints may be more common than previously thought . The postdonation interview is a good tool for defining the blood donor 's experience . It can also be used to evaluate and potentially improve blood donor safety and comfort BACKGROUND Blood supplies in Greece are insufficient to meet the high transfusion needs arising from car accidents and treatment of thalassaemia . This study was design ed to determine Greeks ' opinions about blood donation , in order to identify the reasons for the lack of motivation to donate and allow experts to establish better recruitment campaigns for the enrichment of the donor pool , based on our findings . MATERIAL S AND METHODS The opinions of r and omly selected Greek citizens ( n=800 ) about volunteer blood donation were assessed by means of a st and ardised , anonymous question naire . The results were analysed using the χ(2 ) test and Spearman 's correlation coefficient . RESULTS With regards to attitudes towards intention to donate , only 7.1 % were indifferent , while 88.0 % of the individuals believed that donating blood was an " offer " . Reasons for not donating mainly involved safety ( 36.0 % ) and fear ( 24.0 % ) , whereas need ( 77.9 % ) was the most fundamental positive motivation . Of the people enrolled in the present study , 10.0 % were active donors , 31.3 % occasional donors , 15.0 % rare donors and 36.6 % non-donors . DISCUSSION The considerable percentages of occasional and rare donors in comparison with the low proportion of active donors in the Greek donor pool indicates that " need " is a more important motivation for blood donation than altruism in Greece . These results could be useful for establishing advertising campaigns on blood donation and for a more direct approach to the population , aim ing for a change in mentality in favour of active blood donation 
    Output:
    
RESULTS Among 28 identified articles , the most frequently cited motivators for male blood product donation were as follows : altruism ; positive attitude towards incentives ; health check(s ) ; subjective norms .
Altruism was less pronounced among males compared with females and was combined with ' warm glow ' in novice males ( impure altruism ) .
Perceived health benefits and incentives ( e.g. coffee mugs ) were stronger motivators of males than females .