Once they have gained new skills, HCAs often need replacing, because they no longer perform the tasks they were originally employed for, the researchers claim.
Assistants with no medical qualifications will often want training that must be funded by the practice in areas where PCT budgets are tight.
Also, HCAs may not want to develop further responsibilities without being adequately rewarded, the researchers warn.
The research concludes by saying that although HCAs make a valuable contribution to patient care in a hospital setting, their effectiveness in general practice 'cannot be assumed'.
HCAs can help increase the time health professionals spend on patients with complex needs, however, they can often confuse their roles and work beyond their remit, the authors suggest.
BJGP Practice 2008; 58: 118-24, live links at www.healthcarerepublic.com.