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2004 Data:
 Trends
in new users of Ecstasy, LSD, PCP and other hallucinogens
2003 Data:
Trends
in new users of Ecstasy, LSD, PCP and other hallucinogens
2002
Data on Incidence (New Users): Hallucinogens
- The
incidence of hallucinogen use has exhibited two notable periods of increase. Between
1966 and 1970, the annual number of initiates rose almost sixfold, from 168,000
to 956,000. This increase was driven primarily by use of LSD. The second period
of increase in first-time hallucinogen began in 1992 when there were approximately
706,000 new users. By 2000, the number of initiates rose to 1.7 million, which
is similar to the number for 2001 (1.6 million). The hallucinogen increase in
the 1990s appears to have been driven by increases in use of Ecstasy (i.e., MDMA)
(Figure 6.2).
- Initiation
of Ecstasy use has been rising since 1993, when there were 168,000 new users.
There were 1.9 million initiates in 2000 and 1.8 million in 2001 (not a statistically
significant decline).
- LSD
incidence dropped from 958,000 new users in 2000 to 606,000 in 2001.
Figure
6.2 Annual Numbers of New Users of Ecstasy, LSD, and PCP: 1965–2001
 D
2001
Data: Trends in Initiation of Ecstasy and Other Hallucinogens Estimates
of substance use incidence, or initiation (i.e., the number of new users during
a given year), provide another measure of the Nation's substance use problem.
Where prevalence estimates describe the extent of current use of substances, incidence
data describe emerging patterns of use, particularly among young people. In the
past, increases and decreases in incidence have usually been followed by corresponding
changes in the prevalence of use, particularly among youths. The
incidence estimates in this report are based on National Household Survey on Drug
Abuse (NHSDA) data from 1999, 2000, and 2001 collected with computer-assisted
interviewing methods. These data should not be compared with previously published
NHSDA data based on paper-and-pencil interviewing methods. Not only is the mode
of data collection different for the incidence estimates produced prior to the
1999 NHSDA, but the estimation methodology has been revised as well. The estimation
methodology is described in Appendix
B in Volume II and summarized below. The
incidence estimates are based on the NHSDA questions on age at first use, year
and month of first use for recent initiates, the respondent's date of birth, and
the interview date. Using this information along with editing and imputation when
necessary, an exact date of first use is determined for each substance used by
each respondent. For age-specific incidence rates, the period of exposure is defined
for each respondent and age group for the time that the respondent was in the
age group during the calendar year. Incidents of first use also are classified
by year of occurrence and age at the date of first use. By applying sample weights
to incidents of first use, estimates of the number of new users of each substance
for each year are developed. These estimates include new users at any age (including
those younger than age 12) and also are shown for two specific age groups—youths
aged 12 to 17 and young adults aged 18 to 25. In addition, the average age of
new users in each year and age-specific rates of first use are estimated. The
incidence rates are presented in this report as the number of new users per 1,000
potential new users because they indicate the rate of new use among persons who
have not yet used the substance (i.e., potential new users). More precisely, the
rates are actually the number of new users per 1,000 person-years of exposure.
This measure is widely used in describing the incidence of disease. The numerator
of each rate is the number of persons in the age group who first used the substance
in the year, while the denominator is the person-time exposure measured in thousands
of years. Each person's drug-specific exposure time ends on the date of first
use of the respective drug. For age-specific estimates, exposure is limited to
time during the year that the person was in the age group. Persons who first used
the substance in a prior year have zero exposure to first use in the current year,
and persons who still have never used the substance by the end of the current
year had a full year of exposure to risk. Because
the incidence estimates are based on retrospective reports of age at first substance
use by survey respondents interviewed during 1999, 2000, and 2001, they may be
subject to several sources of bias. These include bias due to differential mortality
of users and nonusers of each substance, bias due to memory errors (recall decay
and telescoping), and underreporting bias due to social acceptability and fear
of disclosure. See Appendix B in
Volume II for a discussion of these biases. As explained in Appendix B, it
is possible that some of these biases, particularly telescoping and underreporting
because of fear of disclosure, may be affecting estimates for the most recent
years more significantly. To account for this bias in the interpretation of the
trends, a more stringent standard for determining statistical significance involving
estimates from the most recent years (1997 and later) is used in this chapter.
Differences are reported to be statistically significant only if they differ at
the  =.01
level. The usual standard in the rest of the report is the
=.05 level. This is an arbitrary standard that provides some protection against
incorrect conclusions in the face of potential biases that can fluctuate and even
change direction from year to year. A more thorough analysis of the problem will
be conducted in the future. Because
the incidence estimates are based on retrospective reports of age at first use,
the most recent year available for these estimates is 2000, based on the 2001
NHSDA. Estimates for the year 2000 are based only on data from the 2001 survey,
estimates for the year 1999 are based only on data from the 2000 and 2001 surveys,
and estimates for earlier years are based on the combined 1999 to 2001 data. For
two of the measures, first alcohol use and first cigarette use, initiation before
age 12 is common. A 2-year lag in reporting for "all ages" estimates
is applied for these measures because the NHSDA sample does not cover youths under
age 12. The 2-year lag ensures that initiation at ages 10 and 11 is captured in
the estimation. Hallucinogens
- The
incidence of hallucinogen use has exhibited two notable periods of increase. Between
1965 and 1971, the number of initiates rose tenfold, from 90,000 to 900,000. The
second period of increase began in 1990 when there were approximately 600,000
new users. By 2000, the number of initiates rose nearly threefold, to 1.5 million.
- Initiation
of Ecstasy (i.e., MDMA) use has been rising steadily since 1992 (Figure 5.2).
The increase from 1.3 million new users in 1999 to 1.9 million in 2000 was statistically
significant, as were the age-specific increases among 12 to 17 year olds and 18
to 25 year olds. The increase from 1998 to 1999 also was statistically significant,
from 0.7 million to 1.3 million new users, as were the age-specific increases.
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