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Estimation of cocaine consumption in the community: a critical comparison of the results from three complimentary techniques
  1. Malcolm J Reid1,
  2. Katherine H Langford1,
  3. Merete Grung1,
  4. Hallvard Gjerde2,
  5. Ellen J Amundsen3,
  6. Jorg Morland2,
  7. Kevin V Thomas1
  1. 1Norwegian Institute for Water Research, Oslo, Norway
  2. 2Norwegian Institute of Public Health, Oslo, Norway
  3. 3Norwegian Institute for Drug and Alcohol Research, Oslo, Norway
  1. Correspondence to Malcolm J Reid; malcolm.reid{at}


Objectives A range of approaches are now available to estimate the level of drug use in the community so it is desirable to critically compare results from the differing techniques. This paper presents a comparison of the results from three methods for estimating the level of cocaine use in the general population.

Design The comparison applies to; a set of regional-scale sample survey questionnaires, a representative sample survey on drug use among drivers and an analysis of the quantity of cocaine-related metabolites in sewage.

Setting 14 438 participants provided data for the set of regional-scale sample survey questionnaires; 2341 drivers provided oral-fluid samples and untreated sewage from 570 000 people was analysed for biomarkers of cocaine use. All data were collected in Oslo, Norway.

Results 0.70 (0.36–1.03) % of drivers tested positive for cocaine use which suggest a prevalence that is higher than the 0.22 (0.13–0.30) % (per day) figure derived from regional-scale survey questionnaires, but the degree to which cocaine consumption in the driver population follows the general population is an unanswered question. Despite the comparatively low-prevalence figure the survey questionnaires did provide estimates of the volume of consumption that are comparable with the amount of cocaine-related metabolites in sewage. Per-user consumption estimates are however highlighted as a significant source of uncertainty as little or no data on the quantities consumed by individuals are available, and much of the existing data are contradictory.

Conclusions The comparison carried out in the present study can provide an excellent means of checking the quality and accuracy of the three measurement techniques because they each approach the problem from a different viewpoint. Together the three complimentary techniques provide a well-balanced assessment of the drug-use situation in a given community and identify areas where more research is needed.

  • Cocaine
  • Drug Epidemiology
  • Population Survey
  • Oral Fluid Analysis
  • Sewage Analysis

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: and

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