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CD4 cell count and initiation of antiretroviral therapy: trends in seven UK centres, 1997-2003
Insights
Antiretroviral therapy (ART) initiation in routine HIV care generally followed guidelines, but many patients started treatment at lower CD4 counts than recommended. This trend was influenced by viral load and, for injection drug users, nonclinical factors.
Area of Science:
- Clinical Medicine
- Infectious Diseases
- Immunology
Background:
- Treatment guidelines for HIV have evolved, recommending antiretroviral therapy (ART) initiation at lower CD4 cell counts.
- Understanding the real-world timing of ART initiation is crucial for assessing guideline adherence and patient outcomes.
Purpose of the Study:
- To evaluate if the timing of ART initiation in clinical practice aligned with evolving treatment guidelines.
- To identify factors influencing the decision to initiate ART at different CD4 cell counts.
Main Methods:
- Analysis of longitudinal data from 10,820 patients in the UK Collaborative HIV Cohort (UK CHIC) Study (1997-2003).
- Estimation of ART initiation probability based on CD4 count and viral load over time.
- Logistic regression and Kaplan-Meier analysis to assess nonclinical factors and early presenters' ART initiation patterns.
Main Results:
- A trend towards initiating ART at lower CD4 counts (200-500 cells/microL) was observed from 1997-2000, with stabilization thereafter.
- 34% of early presenters initiated ART with CD4 counts below 200 cells/microL.
- Viral load significantly influenced ART initiation, especially at CD4 counts <350 cells/microL. Injection drug use was the sole nonclinical factor linked to earlier ART initiation.
Conclusions:
- ART initiation in the studied clinics generally reflected evolving treatment guidelines.
- A significant proportion of patients initiated ART at CD4 counts lower than recommended, partly due to late presentation, but other factors also contributed.
Objectives:
We examined whether the timing of initiation of antiretroviral therapy (ART) in routine clinical practice reflected treatment guidelines, which have evolved towards recommending starting therapy at lower CD4 cell counts.
Methods:
We analysed longitudinal data on 10,820 patients enrolled in the UK Collaborative HIV Cohort (UK CHIC) Study, which includes seven large clinical centres in south-east England. CD4 cell and viral load measurements performed in the period between 1 January 1997 and 31 December 2003 were classified according to whether ART was subsequently initiated or deferred, to estimate the probability of ART initiation by CD4 count and viral load over time. The effect of nonclinical factors (age, sex, ethnicity, and exposure category) was analysed by logistic regression. Kaplan-Meier analysis was used to estimate the proportion of patients who had initiated ART by a particular CD4 count among 'early' presenters (initial CD4 cell count >500 cells/microL).
Results:
There was a tendency to initiate ART at lower CD4 cell counts over time in the years 1997-2000, especially in the range 200-500 cells/microL, with little change thereafter. An estimated 34% of HIV-infected individuals having presented early initiated ART at a CD4 count <200 cells/microL. We also found an independent influence of viral load, which was particularly pronounced for CD4 <350 cells/microL. Use of injection drugs was the only nonclinical factor associated with initiation of ART at lower CD4 cell counts.
Conclusions:
The initiation of ART in the clinics included in this analysis reflected evolving treatment guidelines. However, an unexpectedly high proportion of patients started ART at lower CD4 counts than recommended, which is only partly explained by late presentation.
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