4 To improve the accuracy of drug and alcohol estimation, a number of statistical calculations and models have been developed, by which data are statistically analysed and reported. Such statistical analysis is usually based on numerous data sets being entered into the equation in order to come up with the most accurate figures.
As can be seen from the above, estimating drug and alcohol use and abuse is fraught with problems. The most accurate information is usually obtained when a number of large studies across populations are combined. It is also usually best practice to combine studies that have used different methodologies and statistical calculations, so as to provide the best and most accurate overview of a drug and alcohol problem within the specified population.
It is also very important to understand precisely what has been assessed. For example, if a study is done on drug and alcohol use, the results are likely to differ from a study on drug and alcohol abuse or even dependence. Which criteria are used to study the population also plays an important role. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, with Text Revision (DSM- IV-TR), published by the American Psychiatric Association (APA), covers all mental disorders and is used extensively within the field of psychiatry. The DSM-IV-TR has specific sets of criteria for alcohol abuse (one of four criteria within the last month) and dependence (three of seven criteria over the last year). However, other diagnostic criteria do exist, and could also be used when such studies are undertaken. This would be particularly relevant when comparing and analysing more than one study, as the study methodologies may differ and the criteria used may relate to a different classification system.
Two important concepts that need to be understood when we estimate the use of drug and alcohol within a population are prevalence and incidence.
1 Prevalence refers to the total number of cases at a particular time point who use, abuse or are dependent on drugs and alcohol. Prevalence is thus usually a cross-sectional count of a specific condition being present. There are different types of prevalence, including point prevalence, which refers to the total number of cases at a specific time point; lifetime prevalence, which refers to the total number of cases within a lifetime, up to the date of the study; and period prevalence, which refers to the total number of cases within a predetermined and well-defined time period.
2 Incidence refers to the number of newly reported cases within a specific and predetermined time period. It is a longitudinal indicator of newly reported cases within a specified time, which is usually defined as a one-year period, but could also be longer or shorter, for example one month or ten years.
Although governments, large organisations, non-governmental organisations and even university departments would like information about drug and alcohol use, accessing these data is costly, cumbersome and time consuming. In South Africa, the situation is complicated further by its being a developing nation that is constrained by a lack of funding, technology and manpower.
United States of America
The United States has access to large epidemiological studies that have estimated the use of drugs and alcohol within their population. Numerous studies by various organisations were done throughout the 1980s, 1990s and early 2000s. These studies sampled many thousands of people across the United States in order to estimate the lifetime prevalence of drug and alcohol use, abuse and dependence.
Depending on which study is analysed, the range of lifetime prevalence for alcohol abuse is between 4.9% and 17.8%, while the lifetime prevalence of alcohol dependence ranges from 5.4% to 14.1%. These average figures do not reflect the significantly higher rate of alcohol abuse and dependence within the male population compared with the relatively lower rate in the female population.
The lifetime prevalence of cannabis abuse and dependence is approximately 11.8%, while the lifetime prevalence for other drug abuse and dependence is relatively low (most studies indicate less than 3.9%, although one study ranged up to 7.9%). The lifetime prevalence of nicotine dependence ranged between 13% and 24%.
South Africa
Although South Africa does not have access to such large studies as the United States, we do have a number of surveys and local studies that have attempted to estimate drug and alcohol use within our country. These studies include authors with various affiliations in different localities, using a range of methodologies and definitions. It is therefore very difficult to provide a comprehensive overview of the drug and alcohol situation within South Africa. The South African studies include a number of household and school surveys, as well as specific studies of commercial sex workers, HIV risk behaviour, drug-injecting patterns, and studies of gay men.
Alcohol in South Africa
Overall, it is clear that South Africa has one of the highest levels of alcohol use in the world. Similarly, this country has one of the most hazardous and harmful patterns of alcohol consumption when compared with other countries worldwide. In this sense, alcohol is associated with a high burden of mortality and morbidity. The lifetime alcohol use is approximately 40%, while the current alcohol use within the last one month is approximately 30%. Approximately 25% to 33% of alcohol users engage in risky drinking, which occurs mostly over weekends. Hazardous and harmful alcohol use in adolescents and young adults ranged from 2% to 17%, with that of adults ranging from 5% to 17%. Such hazardous and harmful alcohol use occurred among men and women in both rural and urban areas, in many provinces and across most racial groups.
When alcohol use among different subpopulations was examined, a number of studies among adolescents found a range of current alcohol use from 21% to 62%, with binge drinking ranging from 14% to 40%. Hazardous or harmful drinking was found to be at 19%. Studies of South African students highlighted a current alcohol use among 22% to 80% of students, with binge drinking in the last month ranging between 6% to 43%, and hazardous or harmful drinking ranging from 17% to 58%.
A study among mine workers revealed that 9.3% used alcohol daily of whom 15.3% were alcohol dependent. A study among farm workers in the Western Cape revealed that 87% were potentially alcohol dependent. A study done at a defence force clinic in Cape Town revealed that 13.3% reported that they engaged in hazardous or harmful drinking. A study in a rural primary outpatient clinic revealed that 19.2% of patients reported that they engaged in hazardous or harmful drinking, while an investigation of a psychiatric hospital clinic’s records found that alcohol abuse was 6.3% among women and 15.1% among men.
Cannabis in South Africa
A number of studies have attempted to estimate the use of dagga in South Africa. Adolescent lifetime cannabis use ranges between 7% and 20%, while current use of cannabis among adolescents ranged between 2% and 9%. Adolescents seem to start using cannabis during