1. M. Ismail, D. Brawley, S. Baguley BASHH Annual Conference 2016
Community Viral Load: A population-based biomarker of HIV disease burden in Scotland
M. Ismail, D. Brawley, S. Baguley
BASHH Annual Conference 2016

2. Introduction
Community viral load (CVL) is an aggregate biological measure of HIV viral load (VL) in a population
Reduction in CVL has been correlated to a decrease in HIV incidence (Das et al, 2010)
CVL is a potential tool that can be used to measure HIV disease burden and inform targeted HIV prevention services to local areas (Castel et al, 2011)

3. Health Protection Scotland
HIV Surveillance System
Monitors all HIV diagnoses in Scotland
Collates HIV monitoring data including viral load and CD4 count based on locally provided data
Does not currently collate CVL data

4. Methods
Retrospective cross-sectional study based on HPS Surveillance Data in 2014
Divided into 3 regions:
North
Central South-East (CSE)
Central South-West (CSW)

5. Methods Baseline demographics CVL within each region calculated as:
Age
Gender
Transmission risk
Year of diagnosis
CVL within each region calculated as:
Mean CVL =
Total CVL =
HIV diagnoses for each region in 2014

6. Baseline Demographics
Aspect
Region (%)
Total (N=4126)
CSE (n=1639)
CSW (n=1749)
North (n=738)
Sex F
446 (27.2)
496 (28.4)
209 (28.3)
1151 (27.9) M
1193 (72.8)
1253 (71.6)
529 (71.7)
2975 (72.1)
Age Group
0 – 24
40 (2.4)
30 (1.7)
15 (2.0)
85 (2.1)
25 – 34
208 (12.7)
303 (17.3)
124 (16.8)
635 (15.4)
35 – 44
439 (26.8)
597 (34.1)
178 (24.1)
1214 (29.4)
45+
952 (58.1)
819 (46.8)
421 (57.0)
2192 (53.1)
Transmission Risk
Heterosexual
602 (36.7)
742 (42.4)
372 (50.4)
1716 (41.6)
IDU
186 (11.3)
134 (7.7)
62 (8.4)
382 (9.3)
MSM
796 (48.6)
808 (46.2)
262 (35.5)
1866 (45.2)
Other
37 (2.3)
48 (2.7)
23 (3.1)
108 (2.6)
Unknown
18 (1.1)
17 (1.0)
19 (2.6)
54 (1.3)
HIV Diagnosis (Year)
1982 – 1991
192 (11.7)
87 (5.0)
45 (6.1)
324 (7.9)
1992 – 2001
362 (22.1)
274 (15.7)
153 (20.7)
789 (19.1)
2002 – 2011
824 (50.3)
1009 (57.7)
366 (49.6)
2199 (53.3)
2011 – 2014
261 (15.9)
379 (21.7)
174 (23.6)
814 (19.7)
No statistically significant difference between regions

7. CVL Data (1)

8. CVL Data (2)
Central South-West region (n=1749):
Highest mean CVL: 20,469 copies/ml, 95% CI [8146 – 32,933]
Lowest % with undetectable VL: 77.9%
Central South-East region (n=1639):
Lowest mean CVL: 16,433 copies/ml, 95% CI [11,978 – 20,888]
Highest % with undetectable VL: 79.4%
North region (n=738)
Mean CVL: 17,380 copies/ml, 95% CI [6466=24,387]
% undetectable VL: 78.5%
Statistically significant difference in mean rank VL and the mean rank logVL between the three regions (both p<0.001)

9. Number of new HIV diagnoses
Time
Number of new HIV diagnoses
CSE
CSW
North
Jan – Mar 2014 14 38 8
Apr – Jun 2014 30 43 27
Jul – Sep 2014 29 59 12
Oct – Dec 2014 31 23 20
Total
104
163 67
Cases/100,000
population
8.55
5.83
4.84

10. CVL v. Incident HIV diagnoses

11. Central South East

12. Central South West

13. North

14. Scotland

15. CVL v. Quarterly HIV Incidence
An increase in mean VL was accompanied by a increase in quarterly incidence of new HIV diagnoses in Scotland however this was not statistically significant (Spearman’s rho = 0.025, p=0.11)
Regional results also not statistically significant
Central South West (Spearman’s rho = 0.062, p=0.01)
Central South East (Spearman’s rho = 0.032, p=0.196)
North (Spearman’s rho = –0.047, p=0.202)

16. Key messages First known study to collate CVL data in Scotland
Significant difference in CVL between regions in Scotland
Non significant correlation between CVL and quarterly HIV diagnoses
Current data set limited - further studies to assess longer time frame with more detailed locality data and avidity results
Impact of study
Further studies

17. Thank you
Glenn Codere at HPS