Increasing drug-related mortality rates over the last decade in Scotland are not just due to an ageing cohort: A retrospective longitudinal cohort study.

BACKGROUND: In Europe, North America, and Australia, mortality due to drug-related (DR) causes amongst people who inject drugs (PWID) is a major issue. Our objective was to characterise temporal trends in DR mortality rates in a large cohort of PWID in Scotland over the past decade, all of whom had been diagnosed with hepatitis C virus (HCV) infection, and to investigate factors associated with DR mortality. METHODS: Retrospective longitudinal cohort study linking Scotland's national HCV Diagnosis Database and deaths registry. The study cohort consisted of all individuals with likely injection drug use-related route of HCV acquisition, who had been diagnosed with HCV between 1991 and 2018, and were alive and aged under 65 years on 1 January 2009. We used Lexis expansion to adjust for ageing cohort effects and calculated the mortality rate from an underlying/contributing DR cause over the period 2009-2018. We fitted Poisson regression models to estimate the temporal trend adjusting for attained age, sex, referral setting, region, and viraemic status at baseline. RESULTS: Amongst the study population (n = 35,065; 236,914 person-years), a total of 1900 DR deaths occurred; the DR mortality rate increased from 5.6/1000 [101 deaths] in 2009 to 12.4/1000 [342] person-years in 2018. Increasing trends were observed for all age-groups except 55-64 years. The overall DR mortality rate was highest for referrals for HCV testing from prison (11.0/1000) and hospital settings (10.0/1000). Mortality increased with calendar time period, with significantly raised adjusted rate ratios (RRs) from 2015 (RR=1.40, 95% CI:1.16-1.69) to 2018 (RR=2.23, 95% CI:1.88-2.64), compared with 2011-2012, for older age (35-44: RR=1.37, 95% CI:1.20-1.56; 45-54: RR=1.32, CI:1.14-1.53) compared with <35 years, for persons diagnosed with HCV since 2009 (RR=1.34, 95% CI:1.21-1.49), and for prison and hospital referrals (RRs of 1.30, 1.37) compared with GP referrals. CONCLUSION: Increasing DR mortality rates in Scotland over the past decade are not just due to an ageing cohort. Harm reduction services will likely need to expand and adapt to reverse the recent upward trends in DR mortality in PWID.

A novel design strategy for nanoparticles on nanopatterns: interferometric lithographic patterning of Mms6 biotemplated magnetic nanoparticles.

Nanotechnology demands the synthesis of highly precise, functional materials, tailored for specific applications. One such example is bit patterned media. These high-density magnetic data-storage materials require specific and uniform magnetic nanoparticles (MNPs) to be patterned over large areas (cm2 range) in exact nanoscale arrays. However, the realisation of such materials for nanotechnology applications depends upon reproducible fabrication methods that are both precise and environmentally-friendly, for cost-effective scale-up. A potentially ideal biological fabrication methodology is biomineralisation. This is the formation of inorganic minerals within organisms, and is known to be highly controlled down to the nanoscale whilst being carried out under ambient conditions. The magnetotactic bacterium Magnetospirillum magneticum AMB-1 uses a suite of dedicated biomineralisation proteins to control the formation of magnetite MNPs within their cell. One of these proteins, Mms6, has been shown to control formation of magnetite MNPs in vitro. We have previously used Mms6 on micro-contact printed (µCP) patterned self-assembled monolayer (SAM) surfaces to control the formation and location of MNPs in microscale arrays, offering a bioinspired and green-route to fabrication. However, µCP cannot produce patterns reliably with nanoscale dimensions, and most alternative nanofabrication techniques are slow and expensive. Interferometric lithography (IL) uses the interference of laser light to produce nanostructures over large areas via a simple process implemented under ambient conditions. Here we combine the bottom-up biomediated approach with a top down IL methodology to produce arrays of uniform magnetite MNPs (86 ± 21 nm) with a period of 357 nm. This shows a potentially revolutionary strategy for the production of magnetic arrays with nanoscale precision in a process with low environmental impact, which could be scaled readily to facilitate large-scale production of nanopatterned surface materials for technological applications.

Nano- and micro-patterning biotemplated magnetic CoPt arrays.

Patterned thin-films of magnetic nanoparticles (MNPs) can be used to make: surfaces for manipulating and sorting cells, sensors, 2D spin-ices and high-density data storage devices. Conventional manufacture of patterned magnetic thin-films is not environmentally friendly because it uses high temperatures (hundreds of degrees Celsius) and high vacuum, which requires expensive specialised equipment. To tackle these issues, we have taken inspiration from nature to create environmentally friendly patterns of ferromagnetic CoPt using a biotemplating peptide under mild conditions and simple apparatus. Nano-patterning via interference lithography (IL) and micro-patterning using micro-contact printing (µCP) were used to create a peptide resistant mask onto a gold surface under ambient conditions. We redesigned a biotemplating peptide (CGSGKTHEIHSPLLHK) to self-assemble onto gold surfaces, and mineralised the patterns with CoPt at 18 °C in water. Ferromagnetic CoPt is biotemplated by the immobilised peptides, and the patterned MNPs maintain stable magnetic domains. This bioinspired study offers an ecological route towards developing biotemplated magnetic thin-films for use in applications such as sensing, cell manipulation and data storage.

The role of APOE-ɛ4 and beta amyloid in the differential rate of recovery from ECT: a review.

Individual biological differences may contribute to the variability of outcomes, including cognitive effects, observed following electroconvulsive treatment (ECT). A narrative review of the research literature on carriage of the apolipoprotein E ɛ4 allele (APOE-ɛ4) and the protein biomarker beta amyloid (Aß) with ECT cognitive outcome was undertaken. ECT induces repeated brain seizures and there is debate as to whether this causes brain injury and long-term cognitive disruption. The majority of ECT is administered to the elderly (over age 65 years) with drug-resistant depression. Depression in the elderly may be a symptom of the prodromal stage of Alzheimer's disease (AD). Carriage of the APOE-ɛ4 allele and raised cerebral Aß are consistently implicated in AD, but inconsistently implicated in brain injury (and related syndromes) recovery rates. A paucity of brain-related recovery, genetic and biomarker research in ECT responses in the elderly was found: three studies have examined the effect of APOE-ɛ4 allele carriage on cognition in the depressed elderly receiving ECT, and two have examined Aß changes after ECT, with contradictory findings. Cognitive changes in all studies of ECT effects were measured by a variety of psychological tests, making comparisons of such changes between studies problematic. Further, psychological test data-validity measures were not routinely administered, counter to current testing recommendations. The methodological issues of the currently available literature as well as the need for well-designed, hypothesis driven, longitudinal studies are discussed.

Uptake of hepatitis C antibody testing in patients with end-stage liver disease in Glasgow, 1993-2007.

Individuals infected with hepatitis C virus (HCV) need to be diagnosed well before developing end-stage liver disease to benefit from treatment. We aimed to ascertain what proportion of cases had been tested for HCV to inform on the effectiveness of current guidelines. Record linkage between national databases of HCV tests, hospital discharges and deaths identified 10,645 persons who were hospitalized or had died with mention of end-stage liver disease in Glasgow, Scotland, between 1993 and 2007. We estimated HCV test uptake and prevalence of HCV infection within the study population. The associations between both HCV test uptake and HCV-antibody status and sex, age group and deprivation quintile were estimated using logistic regression. We found that 43% of those hospitalized (n = 9153) and 23% of those who otherwise died (n = 1492) with first-time mention of end-stage liver disease had been tested for HCV during this period. Test uptake in those hospitalized increased from 13 (95% CI: 12-14%) in 1993-1997 to 58% (56-59%) in 2003-2007. The adjusted odds of being tested for HCV were significantly higher for men (OR=1.3, 95% CI: 1.2-1.5), for ages 25-54 (25-34 years: 2.7, 95% CI: 2.1-3.4; 35-44 years: 2.3, 95% CI: 2.0-2.6; 45-54 years: 1.5, 95% CI: 1.4-1.7) compared with 55+ years, and for those residing in the two most deprived quintiles (1.1, 95% CI: 1.0-1.2). Twenty-eight per cent of the HCV testees aged 25-44 years were HCV infected. These results highlight the continuing need for raising awareness among medical professionals for comprehensive HCV testing in patients with liver disease.

Excess morbidity in the hepatitis C-diagnosed population in Scotland, 1991-2006.

We estimated the excess risk of in-patient hospitalization in a large cohort of persons diagnosed with hepatitis C virus (HCV) infection, controlling for social deprivation. A total of 20 749 individuals diagnosed with HCV in Scotland by 31 December 2006 were linked to the Scottish hospital discharge database, and indirectly standardized hospitalization rates, adjusting for sex, age, year and deprivation were calculated. We observed significant excess morbidity considering episodes for: any diagnosis [standardized morbidity ratio (SMR) 3·4, 95% CI 3·3-3·5]; liver-related diagnoses (SMR 41·3, 95% CI 39·6-43·0); and only non-liver-related diagnoses (SMR 2·14, 95% CI 2·08-2·19). Cox regression analyses of the 2000-2006 data indicated increased relative risks of hospitalization for males [hazard ratio (HR) 1·1, 95% CI 1·0-1·2], older age (per 10 years) (HR 1·55, 95% CI 1·5-1·6), and those testing HIV-positive (HR 1·6, 95% CI 1·3-1·8). This study has revealed substantial excess all-cause and liver-related morbidity in the Scottish HCV-diagnosed population, even after allowing for deprivation.

The influence of hepatitis C and alcohol on liver-related morbidity and mortality in Glasgow's injecting drug user population.

Infection with the hepatitis C virus (HCV) is associated with the development of severe liver disease, but cofactors--namely alcohol abuse--in Scotland's HCV-positive population complicate estimation of the unique contribution of HCV. We compared the risk of hospital admission/death for a liver-related cause in a large cohort of Glasgow's injecting drug users (IDUs) testing HCV-positive with IDUs testing HCV negative. Data for 6566 current/former IDUs who had been tested for anti-HCV and/or HCV RNA by polymerase chain reaction in Greater Glasgow health board between 1993 and 2007 were linked to the national hospitalization database and deaths registry to identify all admissions and deaths from a liver-related condition. Relative risks were estimated using Cox proportional hazards regression for recurrent events. Time at risk was censored at 2 years following an HCV test to address bias owing to unobserved seroconversion. The risk of hospitalization/death from a liver-related or an alcoholic liver-related condition following HCV testing was greater for those IDUs with no prior alcohol-related hospitalization who tested positive [adjusted hazard ratio (HR) = 3.2, 95% CI: 1.5-6.7; 4.9, 95% CI: 1.8-13.1, respectively], compared with those who tested anti-HCV negative, but not for those IDUs with a prior alcohol admission (HR = 0.8, 95% CI: 0.4-1.5; 0.8, 95% CI: 0.4-1.6). There was little evidence for an increased risk of hospitalization/death for an exclusively nonalcoholic liver condition for those testing positive (HR = 1.5, 95% CI: 0.8-2.7), after adjustment for previous alcohol-related admission. Within Glasgow's IDU population, HCV positivity is associated with an increased risk of a liver-related outcome, but this is not observed for those IDUs whose problem alcohol use already increases their risk.

The growing contribution of hepatitis C virus infection to liver-related mortality in Scotland.

The large number of individuals in Scotland who became infected with the hepatitis C virus (HCV) in the 1970s and 1980s leads us to expect liver-related morbidity and mortality to increase in the coming years. We investigated the contribution of HCV to liver-related mortality in the period January 1991 to June 2006. The study population consisted of 26,861 individuals whose death record mentioned a liver-related cause (underlying or contributing). Record-linkage to the national HCV Diagnosis database supplied HCV-diagnosed status for the study population. The proportion diagnosed with HCV among people dying from a liver-related cause rose from 2.8% (1995-1997) to 4.4% (2004-June 2006); the largest increase occurred in those aged 35-44 years at death (7% to 17%). Among all deaths from a liver-related cause, an HCV-positive diagnosis was more likely in those who died in 2001 or later than those who died in 1995-1997 (2001-2003: odds ratio (OR)=1.4, 95% confidence interval (CI): 1.1-1.7; 2004-June 2006: 1.6, 1.3-2.0), and in those who died at under 55 compared with at least 55 years of age. HCV infection represents a significant, growing, public health burden in Scotland in terms of early deaths from liver disease.

Diagnosis of hepatitis C virus infection in Scotland's injecting drug user population.

We estimated the extent of undiagnosed hepatitis C virus (HCV) infection in injecting drug users (IDUs) in Scotland. We used record-linkage to determine HCV diagnosis status for 41 062 current/former IDUs attending drug treatment and support services between 1 April 1995 and 31 March 2006; the extent of undiagnosed HCV infection was estimated by comparing the number HCV-diagnosed to the number HCV-infected (estimated from an unlinked anonymous testing survey of 2141 current/former IDUs). In all, 9145 IDUs (22%) were diagnosed HCV antibody-positive since first attendance at drug services (diagnosis rate of 33.6/1000 person-years, 95% CI 32.7-34.4). By 31 March 2006, of the 19 632 current/former IDUs who had attended drug services and were determined to be living with HCV, an estimated 58% (95% CI 45-62) had not been HCV-diagnosed. It is essential that the deployment of resources for identifying at-risk IDUs with a view to offering antiviral therapy is guided by evidence.

A record-linkage study of the development of hepatocellular carcinoma in persons with hepatitis C infection in Scotland.

We investigated trends in first-time hospital admissions and deaths attributable to hepatocellular carcinoma (HCC) in a large population-based cohort of 22 073 individuals diagnosed with hepatitis C viral (HCV) infection through laboratory testing in Scotland in 1991-2006. We identified new cases of HCC through record-linkage to the national inpatient hospital discharge database and deaths registry. A total of 172 persons diagnosed with HCV were admitted to hospital or died with first-time mention of HCC. Hepatocellular carcinoma incidence increased between 1996 and 2006 (average annual change of 6.1, 95% confidence interval (CI): 0.9-11.6%, P=0.021). The adjusted relative risk of HCC was greater for males (hazard ratio=2.7, 95% CI: 1.7-4.2), for those aged 60 years or older (hazard ratio=2.7, 95% CI: 1.9-4.1) compared with 50-59 years, and for those with a previous alcohol-related hospital admission (hazard ratio=2.5, 95% CI: 1.7-3.7). The risk of individuals diagnosed with HCV developing HCC was greatly increased compared with the general Scottish population (standardised incidence ratio=127, 95% CI: 102-156). Owing to the advancing age of the Scottish HCV-diagnosed population, the annual number of HCC cases is projected to increase, with a consequent increasing burden on the public healthcare system.

Hepatitis C virus infection in Scotland: epidemiological review and public health challenges.

INTRODUCTION: In 2004, Scotland's Health Minister stated that the hepatitis C virus (HCV) "is one of the most serious and significant public health risks of our generation". METHODS: To appreciate the prevention and care challenges posed by HCV in Scotland, we reviewed all country-specific data on i) the prevalence of infection among different populations, ii) the numbers infected with HCV, and iii) the current and future HCV disease burden. RESULTS: An estimated 1% of Scotland's population has HCV; 85-90% of those infected were injecting drug users (IDUs). Reductions in HCV prevalence among young IDUs during the early 1990s suggest that the incidence of HCV had decreased; since then, the absence of further reductions highlight that existing prevention measures are insufficient. Two-thirds of the estimated 37,500 chronically HCV-infected individuals in Scotland remain undiagnosed and two-thirds of this group are former IDUs. An estimated 9,000 former IDUs were living with either moderate or severe HCV disease in 2004; if the current uptake of antiviral therapy continues, this number was estimated to double by 2016. Approximately 1,200 HCV-infected IDUs had developed liver failure by 2004; this figure was predicted to increase to 3,200 by 2020. CONCLUSIONS: Scotland faces three principal public health challenges: i) the prevention of HCV among current IDUs, ii) the diagnosis of HCV-infected persons, particularly those most in need of therapy to prevent severe HCV disease, and iii) the current and future provision of adequate resources to ensure that the movement of patients through the diagnostic and clinical care pathway is optimal.

Predicting incidence of variant Creutzfeldt-Jakob disease from UK dietary exposure to bovine spongiform encephalopathy for the 1940 to 1969 and post-1969 birth cohorts.

BACKGROUND: To investigate variant Creutzfeldt-Jakob disease (vCJD) incubation period, transmission barrier, and short-term vCJD predictions for methionine homozygotes in 1940-1969 and post-1969 birth cohorts by use of gender- and age-specific exposure intensities to bovine spongiform encephalopathy (BSE), based on consumption of beef mechanically recovered meat (MRM) and head meat. METHODS: Simulation (from vCJD infections generated randomly from gender and age-specific dietary exposure intensities to BSE), constrained to equal the 47 and 64 vCJD onsets before 2001 in 1940-1969 and post-1969 birth cohorts, was used to estimate lognormal (and other) incubation mean and standard deviation which fitted the calendar year distribution of observed vCJD onsets; and to explore exponential decay in susceptibility to infection with age above 15 years. RESULTS: For the post-1969 birth cohort, the best-fitting lognormal incubation period mean of 11 years (SD 1.5 years and 195 infections) was associated with 194 vCJD onsets (64 before 2001, 105 in 2001-2005, and 25 in 2006-2010). About one-fifth of simulated vCJD onsets before 2001 arose from infections in 1990-1996; age and gender of simulated and observed vCJD patients agreed closely. For the 1940-1969 birth cohort, well-fitting lognormal means ranged widely, the marginally best fitting being 26 years (SD 16.5 years and 382 infections; 47 vCJD onsets before 2001, 58 in 2001-2005, and 63 in 2006-2010). An age-dependent susceptibility function was required to match the age distribution of vCJD patients in the 1940-1969 birth cohort. CONCLUSIONS: About three-fifths of predicted vCJD onsets are expected to be in males, and nearly two-thirds of vCJD onsets in 2001-2005 are expected to be in post-1969 birth cohort according to best-fitting predictions.

UK bovine carcass meat consumed as burgers, sausages and other meat products: by birth cohort and gender.

BACKGROUND: The most likely human exposure to bovine spongiform encephalopathy (BSE) is dietary, through beef mechanically recovered meat (MRM) and head meat used in burgers, sausages and other meat products. The majority, reportedly 90% of beef MRM and 80% of head meat, was used in burgers. To enable quantification of UK dietary exposure to BSE, we quantified bovine carcass meat consumed as burgers, sausages and other meat products by birth cohort, gender and calendar period (1980-1989, 1990-1996). METHODS: Synthesis of dietary data (cross-sectional National Dietary and Nutrition Surveys, and serial National Food Surveys and Realeat Surveys) to simulate weekly consumption by one-thousandth of the UK population in each year from 1980 to 1996. FINDINGS: In 1980-1989, the highest number of consumers (per 7 days) of all three food groups was in the 1940-1969 birth cohort - averaging 3.7 million male consumers of burgers, 2.6 million of sausages and 8.5 million of other meat products. The post-1969 birth cohort had the next highest number of consumers of burgers (1.8 million males). In 1990-1996, consumer numbers declined for the two older cohorts, most strikingly for burgers (down to 2.5 million males in the 1940-1969 cohort). The 1940-1969 cohort retained the highest number of consumers of sausages and other meat products, and second place for burgers. Male consumption was higher, even in the pre-1940 birth cohort where, for demographic reasons, female consumers outnumbered males. In the post-1969 birth cohort, female consumption of bovine carcass meat weight as burgers increased from 68 tonnes in 1980-1989 to 81 tonnes in 1990-1996, and male consumption increased more markedly (by 41%) from 84 tonnes to 119 tonnes; and similarly for other meat products. INTERPRETATION: Properly marshalled age-group and gender-specific consumption data contribute to a clearer understanding of the demography of those who were at risk of dietary exposure to BSE and of when their exposure intensity was greatest. Other countries may need to consider using dietary data to model their human BSE exposure from UK and other BSE-affected regions.

UK dietary exposure to BSE in beef mechanically recovered meat: by birth cohort and gender.

BACKGROUND: Meat recovered mechanically from bovine vertebral columns for use in burgers, sausages and other meat products may have been contaminated with bovine spongiform encephalopathy (BSE) from recovered spinal cord and dorsal root ganglia (DRG). We quantified UK exposure to BSE in beef mechanically recovered meat (MRM) by birth cohort (born pre-1940, in 1940-1969, post-1969), gender and calendar period (1980-1989, 1990-1996) because information on any two of BSE exposure intensity, vCJD incubation period and the new cases of vCJD tells us about the third. METHODS: Synthesis of evidence on BSE epidemiology, MRM production, infectivity in spinal cord and DRG, and UK dietary consumption. FINDINGS: Production of beef MRM peaked at 5000 tonnes in 1987, was nil in 1989 but recovered to 2000 tonnes in 1995 when it ceased altogether; reportedly 90% was used in burgers. Mean weight of spinal cord recovered per carcass was 3.3 g (95% credible interval 0.24-12.02 g) before the specified bovine offal (SBO) legislation and 1.5 g (0.02-8.30 g) after the legislation; whereas recovered weight of DRG (as infectious as spinal cord) was 27 g. Recovery of spinal cord from 1-year pre-clinical bovines peaked in 1988 at 238 g and of DRG in 1993 at 4250 g (medians). Median infectivity (5th and 95th percentiles) consumed in beef MRM was 33 250 (30 550-35 950), 65 600 (60 250-71 050) and 14 350 (13 150-15 600) bovine oral (Bo) ID50 units for the post-1969, 1940-1969 and pre-1940 birth cohorts in 1980-1989; and 44 250 (41 300-47 350), 39 600 (37 100-42,400) and 8750 (8100-9350) Bo ID50 units in 1990-1996. Males consumed almost 58% of infectivity in both periods. If the worst-case level of infectivity pertained, exposure, instead of halving in 1990-1996, would be sustained at around its 1980-1989 level for the two older birth cohorts and would have doubled in 1990-1996 for the post-1969 birth cohort. INTERPRETATION: SBO legislation in 1989 contributed only a 6% reduction in the infectivity in beef MRM. Salient sensitivity issues are highlighted.

UK dietary exposure to BSE in head meat: by birth cohort and gender.

BACKGROUND: UK dietary exposure in 1980-1996 to the bovine spongiform encephalopathy (BSE) infectious agent through the consumption of beef mechanically recovered meat (MRM) contained in burgers, sausages and other meat products has already been quantified by birth cohort (born pre-1940, 1940-1969 or post-1969) and gender. In this paper, similar quantification is undertaken for the consumption of bovine head meat. METHODS: Synthesis of evidence on clinical BSE bovines, on bovines slaughtered in the last year of their BSE incubation period, brain contamination during head meat production, brain infectivity (option 1: 1-year preclinical bovine 54% as infectious as clinical BSE bovine; option 2: 1-year pre-clinical bovine as infectious as clinical BSE bovine) and 1980-1996 UK dietary consumption of head meat in burgers, sausages and other meat products. FINDINGS: Median infectivity consumed in head meat was 49 900 (67 800 for infectivity option 2), 96 200 (126 900) and 24950 (32 800) bovine oral (Bo) ID 50 units for the post-1969, 1940-1969 and pre-1940 birth cohorts in 1980-1989; and 143 950 (266 550 for infectivity option 2), 150 900 (279 500) and 38 350 (71 250) Bo ID50 units in 1990-1996. Males consumed almost 58% of infectivity in 1980-1996. For all three birth cohorts, exposure to BSE in head meat was higher in 1990-96 for both infectivity options. Median infectivity consumed in head meat and beef MRM was 83 150 (109 000 for infectivity option 2), 161 900 (207 450) and 39 300 (50 450) Bo ID50 units for the post-1969, 1940-1969 and pre-1940 birth cohorts in 1980-1989; and 188 200 (348 700), 190 600 (353 050) and 47 200 (87 550) Bo ID50 units in 1990-1996. INTERPRETATION: Males consumed almost 58% of BSE infectivity in head meat and beef MRM, which is consistent with 60 males of 113 variant Creutzfeldt-Jakeb disease (vCJD) onsets to 30 November 2001. If vCJD onsets to that date had all been infected in 1980-1989, 65 of 113 vCJD onsets in the post-1969 cohort are not consistent with its BSE exposure in 1980-1989 unless the vCJD incubation period or susceptibility depends on age, or another exposure is involved. Experimental data are needed to identify which brain material contaminates head meat, and further pathogenesis data are needed to determine the corresponding infectivity. Other salient sensitivity issues are highlighted.

Rationale and cost-efficiency compared for urine or saliva testing and behavioural inquiry among UK offender populations: injectors, arrestees and prisoners.

BACKGROUND: Costs, methodology and efficiency at obtaining behavioural information and biological sample to be tested for blood-borne viruses or illegal drugs are compared for UK surveys of offender populations: injectors in the community or attending drug agencies, arrestees and prisoners. METHODS: Arrestee surveys use extensive behavioural interview + urine sample and measure a key performance indicator in UK's Drugs Strategy. They have low efficiency (urine sample for drugs testing available from under 60% of eligible arrestees) at high cost (pound sterling 110-190 or 350 per urine sample and at least pound sterling 500-800 per injector). Random mandatory drugs testing of prisoners has the highest efficiency (because refusals are punishable), but the cost is high (pound sterling 110-120 per urine sample and pound sterling 300-500 per injector) and behavioural data are lacking. Prisoner surveys use self-completion questionnaire + saliva sample. They guarantee demonstrable anonymity in estimating the prevalence of blood-borne viruses and prisoners' associated risk behaviours, have high efficiency (saliva sample from over 80% of inmates) at low cost (pound sterling 30 per saliva and pound sterling 70-110 per injector), but behavioural data are limited to risk factors for blood-borne viruses. Low cost also characterises comprehensive interview + saliva sample from injectors in the community (pound sterling 90 per saliva sample, all from injectors) but efficiency cannot be assessed because the sampling frame of eligible injectors is not known. Voluntary unlinked anonymous surveys of injectors at drug agencies use self-completion questionnaire + saliva sample to be tested for blood-borne viruses. They are the least costly at pound sterling 43 per injector and moderately efficient with two-thirds volunteer rate by eligible injectors. DISCUSSION: For scientific added-value, we recommend co-location of survey types geographically and temporally; a common core set of behavioural questions; saliva sample as well as (and, eventually, instead of) the less acceptable urine sample. Survey methodologies for measuring key performance indicators should stand up to scrutiny in terms of openness, design credentials, statistical power, and costs. We examine how participation bias or inadequate survey size can compromise the effective monitoring of a key performance indicator.