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SpeedyCeus
The National Survey on Drug Use and Health continues with this section on the Initiaiton of Substance Use...
5. Initiation of Substance Use
Information on substance use initiation, also known as incidence or first-time use, is important for policymakers and researchers. Measures of initiation are often leading indicators of emerging patterns of substance use. They provide valuable information that can be used in the assessment of the effectiveness of current prevention programs and in focusing prevention efforts.
With its large sample size and oversampling of youths aged 12 to 17 and young adults aged 18 to 25, the National Survey on Drug Use and Health (NSDUH) provides a variety of estimates related to substance use initiation based on questions on age, year, and month at first use. Using this information, along with the interview date and the respondent's date of birth, a date of first use is determined for each substance used by a respondent. Estimates of the number of initiates, rates of initiation, and average age at first use can be constructed for specific time periods.
Because of concerns about the validity of trend estimates of incidence based on long recall periods (Gfroerer, Hughes, Chromy, Heller, & Packer, 2004), this report only presents estimates of initiation occurring in the 12 months prior to the interview date. Individuals who initiated use within the past 12 months are defined as recent or past year initiates. Estimates for each year are produced independently based on the data from the survey conducted that year. One caveat of this approach is that because the survey interviews persons aged 12 or older and asks about the past 12 months, the initiation estimates will represent some, but not all of initiation at age 11, and no initiation occurring at age 10 or younger. This underestimation problem primarily affects estimates of initiation for cigarettes, alcohol, and inhalants because they tend to be initiated at a younger age than other substances. See Section B.4.1 in Appendix B for further discussion of the methods and bias in initiation estimates.
There are some important issues that readers need to be aware of when interpreting these NSDUH incidence estimates. First, note that some tables and analyses are based on the ages of initiates at the time of interview, while others focus on the age at the time of first substance use. This can have a large impact on estimates, so readers should pay close attention to the approach used in each situation. Titles and notes on tables document which method applies. Regarding the age at first use estimates, means, as measures of central tendency, are heavily influenced by the presence of extreme values in the data. Thus, for the purposes of this report and unless specified otherwise, the mean age at initiation pertains to persons aged 12 to 49. This constraint was implemented so that the mean age estimates reported would not be influenced by those few respondents who were past year initiates at age 50 or older. Note that this constraint only affects estimates of mean age at initiation; other estimates in this chapter, including the number and prevalence of past year initiates, are among all persons aged 12 or older.
An important consideration in looking at incidence estimates across different drug categories is that substance users typically initiate use of different substances at different times in their lives. Thus, the estimates for specific illicit drugs cannot be added to obtain the number of illicit drug initiates, because, for example, most of the cocaine initiates had previously used marijuana or other drugs and therefore would be represented in the illicit drug initiate estimates for a prior year. Similarly, the estimates of crack initiation are not a subset of the estimates of cocaine initiation, as some persons would have used powder cocaine prior to using crack. To help clarify this aspect of the incidence data, additional tables have been generated to identify which specific illicit drug was used at the time of first use of any illicit drug. These new estimates are discussed below in the first section of this chapter.
The prevalence estimates for nonmedical use of psychotherapeutic drugs, stimulants, and methamphetamine discussed in Chapter 2 take account of data from new items on methamphetamine use that were added to the noncore section of the survey in 2005 and 2006 to capture information on methamphetamine users who failed to recognize the drug when it was presented in the context of prescription drugs in the core stimulants module. The drug use initiation estimates in this chapter, however, are based on data only from the core section of the questionnaire and do not take account of data from new items on the initiation of methamphetamine use that were added to the noncore section in 2007 following up on the additional methamphetamine users identified in the questions introduced in 2005 and 2006. See Section B.4.6 in Appendix B of this report for details.
Initiation of Illicit Drug Use
- In 2007, an estimated 2.7 million persons aged 12 or older used an illicit drug for the first time within the past 12 months; this averages to more than 7,000 initiates per day. This estimate was not significantly different from the number in 2006 (2.8 million). Three fifths of initiates (60.1 percent) were younger than age 18 when they first used, and 54.1 percent of new users were female. The average age at initiation among persons aged 12 to 49 was 18.0 years.
- In 2007, of the 2.7 million persons aged 12 or older who used illicit drugs for the first time within the past 12 months, a majority reported that their first drug was marijuana (56.2 percent) (Figure 5.1). Nearly one third initiated with psychotherapeutics (30.6 percent, including 19.0 percent with pain relievers, 6.5 percent with tranquilizers, 4.1 percent with stimulants, and 1.1 percent with sedatives). A sizable proportion reported inhalants (10.7 percent) as their first drug, and a small proportion used hallucinogens as their first illicit drug (2.0 percent). The percentage of past year illicit drug initiates whose first drug was tranquilizers increased from 2.4 percent in 2002 to 6.5 percent in 2007, while the percentage whose first drug was Ecstasy decreased from 1.9 percent in 2002 to 0.6 percent in 2007.
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Figure 5.1 Specific Drug Used When Initiating Illicit Drug Use among Past Year Initiates of Illicit Drugs Aged 12 or Older: 2007
Comparison, by Drug
- The specific drug categories with the largest number of recent initiates among persons aged 12 or older were nonmedical use of pain relievers (2.1 million) and marijuana use (2.1 million), followed by nonmedical use of tranquilizers (1.2 million), cocaine (0.9 million), Ecstasy (0.8 million), inhalants (0.8 million), and stimulants (0.6 million) (Figure 5.2).
- Among persons aged 12 to 49, the average age at first use of inhalants in 2007 was 17.1 years; it was 17.6 years for marijuana, 20.2 years for cocaine, 20.2 years for Ecstasy, 21.2 years for pain relievers, and 24.5 years for tranquilizers (Figure 5.3).
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Figure 5.2 Past Year Initiates for Specific Illicit Drugs among Persons Aged 12 or Older: 2007
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Figure 5.3 Mean Age at First Use for Specific Illicit Drugs among Past Year Initiates Aged 12 to 49: 2007
Marijuana
- In 2007, there were 2.1 million persons who had used marijuana for the first time within the past 12 months; this averages to approximately 6,000 initiates per day. This estimate of past year initiates in 2007 was about the same as the number in 2006 (2.1 million), 2005 (2.1 million), 2004 (2.1 million), 2003 (2.0 million), and 2002 (2.2 million) (Figure 5.4).
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Figure 5.4 Past Year Marijuana Initiates among Persons Aged 12 or Older and Mean Age at First Use of Marijuana among Past Year Marijuana Initiates Aged 12 to 49: 2002-2007
+ Difference between this estimate and the 2007 estimate is statistically significant at the .05 level.
1 Mean-age-at-first-use estimates are for recent initiates aged 12 to 49.
- Most (62.2 percent) of the 2.1 million recent marijuana initiates were younger than age 18 when they first used. Among youths aged 12 to 17, an estimated 4.6 percent had used marijuana for the first time within the past year, similar to the rate in 2006 (4.7 percent).
- As a percentage of those aged 12 to 17 who had not used marijuana prior to the past year, the youth marijuana initiation rate in 2007 (5.2 percent) was similar to the rate in 2006 (5.4 percent).
- In 2007, the average age at first marijuana use among recent initiates aged 12 to 49 was 17.6 years, which was similar to the average in 2006 (17.4 years) (Figure 5.4). Among recent initiates aged 12 or older who initiated use prior to the age of 21, the mean age at first use was 16.2 years in 2007, which was not significantly different from the estimate (16.1 years) in 2006.
Cocaine
- In 2007, there were 906,000 persons aged 12 or older who had used cocaine for the first time within the past 12 months; this averages to approximately 2,500 initiates per day. This estimate was not significantly different from the number in 2006 (977,000).
- Most (66.5 percent) of the 0.9 million recent cocaine initiates were 18 or older when they first used. The average age at first use among recent initiates aged 12 to 49 was 20.2 years, which was similar to the average age in 2006 (20.3 years).
Heroin
- In 2007, there were 106,000 persons aged 12 or older who had used heroin for the first time within the past 12 months. The average age at first use among recent initiates aged 12 to 49 was 21.8 years in 2007. There were no significant changes in the number of initiates or in the average age at first use from 2006 to 2007.
Hallucinogens
- In 2007, there were 1.1 million persons aged 12 or older who had used hallucinogens for the first time within the past 12 months. This estimate was not significantly different from the estimate in 2002, 2004, 2005, and 2006. However, the estimate was significantly higher than the estimate in 2003 (886,000).
- There was no significant change between 2006 and 2007 in the number of past year initiates of LSD (264,000 and 270,000, respectively).
- There was no significant change in the past year initiates of Ecstasy between 2006 (860,000) and 2007 (781,000). The number of past year Ecstasy initiates in 2007, however, was significantly lower than the estimate in 2002 (1.2 million), but higher than the estimate in 2003 (642,000), 2004 (607,000), and 2005 (615,000) (Figure 5.5). Most (61.2 percent) of the recent Ecstasy initiates in 2007 were aged 18 or older at the time they first used Ecstasy. The corresponding figure was 70.1 percent in 2006. Among past year initiates aged 12 to 49, the average age at initiation of Ecstasy in 2007 was 20.2 years, similar to the average age in 2006 (20.6 years).
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Figure 5.5 Past Year Ecstasy Initiates among Persons Aged 12 or Older and Mean Age at First Use of Ecstasy among Past Year Ecstasy Initiates Aged 12 to 49: 2002-2007
+ Difference between this estimate and the 2007 estimate is statistically significant at the .05 level.
1 Mean-age-at-first-use estimates are for recent initiates aged 12 to 49.
Inhalants
- In 2007, there were 775,000 persons aged 12 or older who had used inhalants for the first time within the past 12 months; 66.3 percent were under age 18 when they first used. There was no significant difference in the number of inhalant initiates between 2006 and 2007. However, there was a significant increase in the average age at first use among recent initiates aged 12 to 49 from 2006 (15.7 years) to 2007 (17.1 years).
Psychotherapeutics
- Psychotherapeutics include the nonmedical use of any prescription-type pain relievers, tranquilizers, stimulants, or sedatives. Over-the-counter substances are not included. In 2007, there were 2.5 million persons aged 12 or older who used psychotherapeutics nonmedically for the first time within the past year, which averages out to around 7,000 initiates per day. The numbers of new users of specific classes of psychotherapeutics in 2007 were 2.1 million for pain relievers, 1.2 million for tranquilizers, 642,000 for stimulants, and 198,000 for sedatives. There was a significant decrease in the number of past year initiates of stimulants from 2006 (845,000) to 2007 (642,000), but there were no significant changes in the estimates for the remaining psychotherapeutics between these years. The estimated number of past year initiates of nonmedical pain reliever use declined from 2.5 million in 2003 to 2.1 million in 2007.
- The average age at first nonmedical use of any psychotherapeutics among recent initiates aged 12 to 49 was 21.8 years. More specifically, it was 21.2 years for pain relievers, 21.9 years for stimulants, 24.5 years for tranquilizers, and 24.2 years for sedatives.
- In 2007, the number of new nonmedical users of OxyContin® aged 12 or older was 554,000, with an average age at first use of 24.0 years among those aged 12 to 49. These estimates are similar to those for 2006 (533,000 and 22.6 years, respectively).
- The number of recent new users of methamphetamine among persons aged 12 or older was 157,000 in 2007 (Figure 5.6). This estimate was significantly lower than the estimate in 2002 (299,000), 2003 (260,000), 2004 (318,000), and 2006 (259,000). The average age of new methamphetamine users aged 12 to 49 in 2007 was 19.1 years, not significantly different from the average ages in 2002 through 2006.
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Figure 5.6 Past Year Methamphetamine Initiates among Persons Aged 12 or Older and Mean Age at First Use of Methamphetamine among Past Year Methamphetamine Initiates Aged 12 to 49: 2002-2007
+ Difference between this estimate and the 2007 estimate is statistically significant at the .05 level.
1 Mean-age-at-first-use estimates are for recent initiates aged 12 to 49.
Alcohol
- In 2007, there were 4.6 million persons aged 12 or older who had used alcohol for the first time within the past 12 months; this averages to approximately 12,500 initiates per day. The number of past year alcohol initiates in 2007 was significantly greater than the estimate in 2002 (3.9 million) and 2003 (4.1 million), but similar to the numbers in 2004 (4.4 million), 2005 (4.3 million), and 2006 (4.4 million).
- Most (85.9 percent) of the 4.6 million recent alcohol initiates were younger than age 21 at the time of initiation.
- In 2007, the average age at first alcohol use among recent initiates aged 12 to 49 was 16.8 years, similar to the corresponding 2006 estimate (16.6 years). The mean age at first use among recent initiates aged 12 or older who initiated use prior to the age of 21 was 15.8 years, which was the same as the 2006 estimate.
Tobacco
- The number of persons aged 12 or older who smoked cigarettes for the first time within the past 12 months was 2.2 million in 2007, which was significantly lower than the estimate in 2006 (2.4 million) but significantly higher than the estimate for 2002 (1.9 million) and 2003 (2.0 million) (Figure 5.7). The 2007 estimate averages out to approximately 6,100 new cigarette smokers every day. Most new smokers in 2007 were under age 18 when they first smoked cigarettes (59.7 percent).
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Figure 5.7 Past Year Cigarette Initiates among Persons Aged 12 or Older, by Age at First Use: 2002-2007
+ Difference between this estimate and the 2007 estimate is statistically significant at the .05 level.
- In 2007, among recent initiates aged 12 to 49, the average age of first cigarette use was 16.9 years, similar to the average in 2006 (17.1 years).
- Of those aged 12 or older who had not smoked cigarettes prior to the past year, the past year initiation rate for cigarettes was 2.5 percent in 2007, significantly lower than the rate in 2006 (2.9 percent). Among youths aged 12 to 17 years who had not smoked cigarettes prior to the past year, incidence showed a significant decrease between 2006 (6.6 percent) and 2007 (5.9 percent). Among males aged 12 to 17, the decrease in the past year initiation rate from 6.1 percent in 2002 to 5.7 percent in 2007 was not statistically significant, but among females, the decrease from 7.4 percent in 2002 to 6.0 percent in 2007 was statistically significant (Figure 5.8).
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Figure 5.8 Past Year Cigarette Initiation among Youths Aged 12 to 17 Who Had Never Smoked, by Gender: 2002-2007
+ Difference between this estimate and the 2007 estimate is statistically significant at the .05 level.
- In 2007, the number of persons who had started smoking cigarettes daily within the past 12 months was 1.0 million. This estimate is similar to the estimates for 2002 (1.0 million), 2003 (1.1 million), 2004 (1.1 million), 2005 (1.0 million), and 2006 (1.1 million). Of these new daily smokers in 2007, 40.7 percent, or 400,000, were younger than age 18 when they started smoking daily. This figure averages to approximately 1,100 initiates of daily smoking under age 18 every day.
- The average age of first daily smoking among new daily smokers aged 12 to 49 in 2007 was 19.2 years. This was not significantly different from the average in 2006 (18.9 years).
- In 2007, there were 3.1 million persons aged 12 or older who had used cigars for the first time in the past 12 months, the same as the number in 2006. However, this estimate reflects a significant increase in the number of initiates from 2003 (2.7 million). Among past year cigar initiates aged 12 to 49, the average age at first use was 20.5 years in 2007, which was not significantly different from the estimate in 2006 (19.9 years).
- The number of persons aged 12 or older initiating use of smokeless tobacco in the past year was 1.3 million in 2007, which was the same as the estimate in 2006 and not significantly different from the estimate in 2005 (1.1 million). However, the estimated number of past year initiates of smokeless tobacco use in 2007 was at least 30 percent higher than the estimate in 2002 (951,000), 2003 (928,000), and 2004 (999,000). About three quarters (74.2 percent) of new initiates in 2007 were male, and a little more than half (52.5 percent) were under age 18 when they first used.
- The average age at first smokeless tobacco use among recent initiates aged 12 to 49 in 2007 was 18.0 years. Averages were 17.4 years for males and 19.7 years for females.
This is the end of this section. The next section look into the risk factors attributed to drug use and measure to help prevent youth drug use.
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