Measuring the incidence, prevalence, and g , p ,genotypes of hepatitis C virus infection among injecting drug users: Are dried blood spots j g g psamples the way forward?

Vivian D. Hope1,2, Matthew Hickman3, Mariangela Bizzarri1, Siew Lin Ngui1, Fortune Ncube1, John V. Parry1. , y

1. Centre for Infections, Health Protection Agency, London, UK. 2 Centre for Research on Drugs & Health Behaviour2. Centre for Research on Drugs & Health Behaviour, London School of Hygiene & Tropical Medicine, University of London, UK. 3. Social Medicine, University of Bristol, Bristol, UK3. Social Medicine, University of Bristol, Bristol, UK

BackgroundBackgroundMonitoring hepatitis C (HCV) infection among injecting drug

(IDU ) b hi d d b diffi lti iusers (IDUs) can be hindered by difficulties in:1. Collecting blood from IDUs:-

Oral fluid samples allow antibody testing but are not suitable for– Oral-fluid samples allow antibody testing, but are not suitable for molecular tests.

– Dried Blood Spot (DBS) samples allow a greater range of tests, including use PCR for HCV RNA and genotypinguse PCR for HCV RNA and genotyping.

2. Obtaining representative samples of IDUs:-– No sampling frame, so use convenience sampling. Potentially biased?– Respondent Driven Sampling (RDS) – a controlled chain-

referral/network approach – has been developed to reduce bias.

This study looks at the utility of using DBS and RDS in monitoring both HCV prevalence and incidence among IDUs in the UKIDUs in the UK.

SettingSettingStudy was undertaken in Bristol in the south west ofBristol in the south west of England: – the sixth largest city in the UK,the sixth largest city in the UK,

with a population of : • 400,000 in the city;

550 000 i th id b• 550,000 in the wider urban area.

– city estimated to have 4,237 IDUs in 2005.

Method – SamplingMethod Sampling• Individuals aged over 15 years resident in Bristol g y

who had injected during the proceeding four weeks were recruited using RDS.

• Target sample size: 300.• Acknowledgements: £10 (€13) for participation, plus

£5 (€6 5) f h f l it t£5 (€6.5) for each successful recruitment.• Participants underwent:

t i t d i t i ( 30 i )– a computer-assisted interview (approx. 30 mins), and provided a DBS sample tested for HCV– provided a DBS sample – tested for HCV antibodies (anti-HCV) & PCR for HCV RNA.

Method – Incidence estimationMethod Incidence estimationIndividuals with DBS samples that were HCV RNA positive

and anti-HCV negative were assumed to be recently infected with HCV.

‘Wi d i d’ f b i HCV RNA iti t ti‘Window period’ from becoming HCV RNA positive to anti-HCV detection was assumed to be between 51 & 75 days.

I id l l t d i th f lIncidence calculated using the formula:(365/T)n

I = N + (365/T)(n/2)

Where: I = incidenceT = windown = number incident infections (HCV RNA positive and

anti-HCV negative)N = number of susceptibles (anti-HCV negatives, including

b th HCV RNA ti d iti )both HCV RNA negatives and positives)

Method - RDSMethod RDS• Seven seeds were recruited:

– came from several locations within the recruitment area.– included four women.– ranged in age from 23 to 36 years. – six produced recruitment waves. – with these producing 2, 3, 5, 5, 12 and 17 waves of recruitment.

• The two most productive seeds where both male, and th d d i f lthe seed producing no waves was female.

• ‘Weights’ were calculated to adjust for the sample. Th th i bl d i l l ti th dj t t i ht– The three variables used in calculating the adjustment weights were: age, homelessness, and crack injection.

Sample characteristicsWeighted (increased=↑; decreased=↓; no change=↔)

– 27% female (↑)27% female (↑)– Median 30 age years (↓)– Median 10 years since first injected (↔)y j ( )– 49% homeless last year (↓)– 32% in prison last year (↓)– 48% injecting crack last month (↓)– 91% injecting opiates last month (↑)– 20% injected amphetamine last month(↑)– 33% main injecting site groin (↔)

0 7% A ti HIV (↓)– 0.7% Anti-HIV +ve (↓)– 32% Anti-HBc +ve (↓)

Anti-HCV prevalenceAnti HCV prevalence53% Anti-HCV +ve (weighted 177/299) (↓)

Other univariable associations with anti-HCV +ve:Other univariable associations with anti HCV +ve: male gender, older age, recent homelessness, past imprisonment, & injecting all or most days.

Estimated HCV IncidencePCR on 115 of 122 anti-HCV negatives.

Un-weighted WeightedWindow period in

da s

Un weighted Weighted

Numberdays Number PCR+ve

Total Incidence %

51 14 115 61 57

75 14 115 46 43

Anti-HCV positivesAnti HCV positivesPCR on 173 of 177 anti-HCV positives.

Among the 173 anti-HCV positives, 70 were HCV RNA ti (42% i ht d)RNA-negative (42% weighted).Suggesting that many had cleared their HCV infection.

Those anti-HCV-positive and RNA-negative had been injecting for longer (median 14 years v 12been injecting for longer (median 14 years v. 12 years; Mann-Whitney U, p=0.044, weighted), but otherwise they were similar to the RNAotherwise they were similar to the RNA-positives.

Genotyping114 of the 117 HCV RNA positives typed

Th f dThe genotypes found were:1a x60, 3 463a x46, 2b x4, 2 2 &2a x2, & 4d x2.

Of the anti-HCV-negative/RNA-positives:13 were 1a and13 were 1a, and 1 was 3a.

A transmission cluster?Phylogenetic analysis of HCV

1076 3a 1079 3a

922 3a 1094 3a

979 3a 1015 3a

1117 3a 1054 3a

1132 3a 891 3a

902NEG 3a 908 3a 904 3a 1032 3a 1082 3a

998 3a

NS5B sequences revealed several clusters among the

t 1 i f ti

998 3a 1092 3a

918 3a 1118 3a

994 3a 1093 3a

1064 3a 1009 3a

1170 3a 1178 3a 1112 3a 1114 3a

980 3a 892 3a 1086 3a

990 3a 1149 3a

965 3a 944 3a 1143 3agenotype 1a infections.

Including one of nine anti-

1143 3a 946 3a 1177 3a 957 3a

1133 3a 985 3a

1063 3a 0978 2a 1002 2a

1176 2b 1125 2b

1020 2b 0962 2b

1108 4d 1074 4 1174 1a 1003 1a

1104 1a 1060 1a

0996 1a

HCV-negative and four anti-HCV-positive

0996 1a 0959 1a 0923 1a 1023 1a

0929 1a 0937 1a

0935 1a 0981 1a 1163 1a 0988 1a

1130 1a 1050NEG 1a

0897 1a 0936 1a 1083 1a 1022 1a

1171 1a 1057 1a

0919 1a 0947 1a

samples. This finding is consistent with a recent t i i l t

0947 1a 1088NEG 1a

0911 1a 0987 1a 0953 1a 1099 1a

1055 1a 1053NEG 1a0975 1a 1035NEG 1a1040 1a 1095 1a

0971 1a 1069 1a

1062 1a 1078 1a 1161 1a 1102 1a

0931 1a 0942 1atransmission cluster.

0 1

0942 1a 1129 1a

1047 1a 1084 1a

1153 1a 0966 1a 1019NEG 1a

0976 1a 0912NEG 1a1039NEG 1a1027NEG 1a1061NEG 1a1120NEG 1a1131NEG 1a1101 1a 1013 1a 1011NEG 1a

1004NEG 1a0.1

The RDS recruitmentrecruitment chains

Anti–HCV +ve Anti-HCV –ve Seeds are larger shapesRNA +RNA +veRNA –veNot PCR-ed

ConclusionsFindings confirm the relatively high anti-HCV prevalence in

BristolBristol.Unadjusted prevalence was similar to that from a previous community survey – this, and similar past studies using convenience sampling, may have over estimated prevalence?estimated prevalence?

Findings also suggest either a high incidence, or possibly the chance capture of a transmission cluster. pIs the possible cluster related to recruitment approach?Are all HCV RNA positive / anti-HCV negatives recent infections? Is window period for DBS similar to that for blood?Is window period for DBS similar to that for blood?

Further development work is indicated on recruitment approaches for use in studies, and on the ‘window period’.pp , p

Currently IDU sero-surveillance uses oral fluids in UK. It could be enhanced by using DBS specimens.

AcknowledgmentsAcknowledgmentsBristol Drugs Project, and particularly Maggie Telfer, forBristol Drugs Project, and particularly Maggie Telfer, for

collaborating with the survey.Steve Jones, and team, for delivering the fieldwork., , gOur colleagues at:

Health Protection Agency, University of Bristol, & Centre for Research on Drugs and Health Behaviour, LSHTM.

And in particular all the individuals who participated in the survey.

The End. Thank you.a you

• Following slides not being used currentlyFollowing slides not being used currently