Dr Matthew Hickman, from Imperial College London, based at Charing Cross Hospital, and one of the authors of the research, comments: "These results could help provide better data on the true number of drug users in the population and help provide the government with a far better surveillance tool than they currently have. Often the true level of drug use is hidden within populations, but this method could be used to provide a more accurate picture."
The researchers analysed data for England and Wales between 1968 and 2000, looking at 7375 deaths in people aged 15-44, which had been coded as drug misuse or accidental opiate overdose, and used a back calculation method to estimate long term trends.
The results suggested that there have been two epidemic periods with the numbers of new opiate and injecting drug users having increased three-fold between 1975 and 1979 and up to five to six-fold between 1987 and 1995. Models looking at recent data suggest the numbers of new opiate users may have recently declined.
The results also suggested the number of current opiate and injecting drug users has continued to rise since the early 1970s, doubling between 1977 and 1982, and possibly rising four-fold from 1987 to 1996 though slowing from 1997.
Dr Daniela de Angelis, from the Health Protection Agency and the MRC Biostatistics Unit, Cambridge, and one of the authors of the research adds: "Although these figures are alarming, they do need to be treated with caution. They were calculated using a method which ideally requires better information on opiate users' death rates and how long they inject for, but the figures do serve to highlight some important issues."
Dr Hickman adds: "These figures point to an alarming rise in the numbers of deaths from drug overdoses, something the government urgently needs to take action on. Rather than just spending money on treating existing drug addicts, there is a need for better health education to stop people becoming addicted in the first place."
The research was funded by the Research and Development Department of Health, with the Office of National Statistics providing the data on deaths over time.