1. San Francisco Department of Public Health
Trends in percent time spent viremic among persons newly diagnosed with HIV, San Francisco, CA, USA,
Alison Hughes, PhD, MPH
Ling Hsu, MPH
Susan Scheer, PhD, MPH
San Francisco Department of Public Health
San Francisco, CA, USA

2. Conflicts of Interest
None to declare.

3. Background
Virologic suppression benefits individuals and reduces transmission.
Risk of sexual HIV transmission increases as HIV viral load increases.
Persons newly diagnosed with HIV are at greater risk of co-morbidities and transmission until ART initiation and sustained viral suppression.

4. Number of new HIV diagnoses and viral suppression by year of diagnosis, San Francisco, 2008-2016.
85%
40%

5. Objectives
Examine the amount of time spent viremic among persons newly diagnosed with HIV in San Francisco.
Determine if any differences by:
Year of HIV diagnosis
Demographic factors
Clinical factors

6. Methods Inclusion criteria: HIV diagnosis during 2008-2016
San Francisco resident at time of diagnosis
Alive 12 months after HIV diagnosis
≥2 viral load tests within 12 months after HIV diagnosis

7. Method for estimating time spent >10000 copies/ml
VL1
VL2
Example for hypothetical individual
Orange shaded area shows the time spent above copies/ml
VL4
124 days spent above copies/ml
34% of the 12 months after HIV diagnosis
VL3 88
124
211
References: Gardner CROI 2014; Marks AIDS 2015; Buchacz CROI 2017

8. Multivariate regression
Analysis Methods
Multivariate regression
Exposure:
year of HIV diagnosis
Outcome:
days spent above each viral threshold in 12 months after diagnosis
(offset parameter=number of days observed)
Covariates:
gender
housing status
transmission category
CD4+ lymphocyte count
race/ethnicity
health insurance type
age
time from HIV diagnosis to ART initiation

9. Transmission category MSM 1862 (73%) 560 (72%) PWID 168 (7%) 41 (5%)
Included
n (%)
Excluded
Total
2556 (100%)
780 (100%)
Gender
Male
2292 (90%)
708 (91%)
Female
183 (7%)
49 (6%)
Trans female
81 (3%)
23 (3%)
Transmission category
MSM 
1862 (73%)
560 (72%)
PWID
168 (7%)
41 (5%)
MSM-PWID
318 (12%)
104 (13%)
Heterosexual
157 (6%)
39 (5%)
Other/Unidentified
51 (2%)
36 (5%)
Age at HIV diagnosis
16-24 years
253 (10%)
114 (15%)
25-29 years
400 (16%)
172 (22%)
30-39 years
798 (31%)
242 (31%)
40-49 years
715 (28%)
170 (22%)
50+ years 
390 (15%)
82 (11%)
Housing status at HIV diagnosis
Homeless
220 (9%)
88 (11%)
Insurance at HIV diagnosis
Public 
648 (25%)
162 (21%)
Private
1065 (42%)
218 (28%)
None
570 (22%)
256 (33%)
Missing
273 (11%)
144 (19%)
Time from HIV diagnosis to ART initiation
0-7 days
316 (12%)
57 (7%)
8-30 days
456 (18%)
25 (3%)
31-90 days
670 (26%)
36 (5%)
days
509 (20%)
65 (8%)
No known ART
605 (24%)
597 (77%)

10. Mean percent time spent above each viral threshold among newly diagnosed persons, San Francisco,

11. Cochran-Armitage test for trend p<0.0001 for each threshold
Percent time spent above each viral threshold during 12 months after HIV diagnosis by year of HIV diagnosis, San Francisco,
Cochran-Armitage test for trend p< for each threshold

12. Multivariable factors associated with person time >200 copies/ml
Characteristic
Adjusted Rate Ratio (95% CI)
Year of HIV diagnosis (numeric)
0.96 (0.95, 0.97)
MSM-PWID (vs MSM)
1.15 (1.06, 1.24)
Age years (vs 50+ years)
1.1 (1, 1.2)
Homeless (vs housed)
1.12 (1.02, 1.22)
CD4 count (vs 500+)
0.87 (0.81, 0.94)
CD4 count (vs 500+)
0.89 (0.83, 0.96)
Time from HIV diagnosis to ART
31-90 days (vs 0-7 days)
1.21 (1.11, 1.32)
days (vs 0-7 days)
1.7 (1.54, 1.86)
No known ART use within 1 year after HIV diagnosis (vs 0-7 days)
1.78 (1.62, 1.95)
*No significant differences by gender, race/ethnicity or insurance type.

13. Limitations Date of diagnosis vs. HIV acquisition
No viral load information before HIV diagnosis
Misclassification of outcome
Assumes linear relationship
Less reliable if great amount of time between VL pairs
Loss to follow-up
Unmeasured confounding
ART prescription vs. adherence
Social factors not recorded in HIV registry

14. Discussion
Lower CD4 count associated with decreased time spent viremic
Results likely underestimate time spent viremic due to exclusion criteria
Newly diagnosed persons with fewer than two viral loads were excluded (23%)
Vulnerable populations, including younger ages and homeless individuals, were more likely to be excluded
Adjusted RRs biased towards null

15. Conclusions
Time spent above each viremic level decreased significantly among newly diagnosed persons from 2008 to 2016 and likely contributed to the decreased HIV incidence observed.
PWID (including MSM-PWID) and younger age spent more person-time viremic.
Homeless individuals spent more person-time >200 copies/ml.