Surveillance Data and Systems

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CD4 and Viral Load Surveillance System

Periodic monitoring of CD4 T-lymphocyte (CD4 cell) counts and HIV viral load are part of the routine clinical management of HIV seropositive patients in Scotland. CD4 cell counts and viral load data on all HIV infected individuals receiving specialised care in Scotland are collected and collated by HPS; information from the CD4 and viral load surveillance system is linked to records of HIV diagnosis (see New Diagnoses of HIV and AIDS). 

CD4 cell counts give a measure of the degree to which an individual’s immune system is ‘compromised’. Measures of viral load indicate how actively HIV is replicating.CD4 cell counts and viral load measures, together, are used by clinicians to decide when to start an infected person on antiretroviral therapy and to help them monitor the effectiveness of particular therapeutic regimens. 

The objectives of the CD4/viral load surveillance are:

  • To monitor access of HIV infected individuals to specialist follow up services and treatment
  • To monitor the proportion of treated HIV infected patients with undetectable viral load
  • To monitor trends in immunosuppression associated with HIV infection
  • To provide estimates of the future numbers of persons with severe HIV disease who will require care (in combination with other data)
  • To provide timely and useful information for the planning of medical services for those affected by HIV.

This surveillance system holds patient identifiable information.

By patient identifiable information we mean details such as name, address or case record number. HPS seeks to limit to a minimum these details and many systems are anonymised, e.g. do not hold individual names and addresses.

Should you wish details of the patient identifiable information held in this system, please contact enquiries.

Further information on data confidentiality can be found on our Information Governance page or can be obtained by contacting the HPS Information Security and Data Protection Officer (Telephone 0141 300 1100).