In the early 1990s, a new music culture called dance spread through numerous countries in the western world. Rave parties or house parties with DJ-directed, fast-paced electronic music and light shows were organized ^[1],^[2]. In The Netherlands, rave parties attract from 500 to 60,000 visitors. Approximately 650,000 youngsters (15–35 year olds) ^[3] attend these events yearly. Several studies have indicated that the use of recreational substances during raves is common, and the majority of visitors use one or more substances ^[1],^[4]–^[13].

In the Netherlands, rave parties are allowed only if strict regulations are met. One of these is that a first aid station is required to take care of rave party attendees with various health-related problems. Here we present an overview of substance-related visits to first aid stations at rave parties in the Netherlands between 1997 and 2008.

This was a prospective observational study of rave-party attendees who presented themselves for help at first aid stations at rave parties during the period 1997–2008. All persons seeking first aid were registered, but only those with substance-related problems were included in this study. Health-related incidents are described, together with length of medical care, severity of the incidents, predictability of symptoms, and short-term risks. Specifically, the following information was collected with regard to rave party attendees who sought help at first aid stations: (1) Length of stay, (2) substances used alone or in combination, and (3) nature of the substance-related problems.

In an unpublished 1996 prospective pilot study of rave-party attendees, those seeking first aid were divided into two groups. The first was a self-care group. These people visited a first-aid station with only minor health-related problems and were not included in the study. The second group visited the first aid station seeking help or advice. For this group, a standard questionnaire was developed to ask about their health-related problems ^[7]. Each person's age and sex and time of arrival at and departure from the first aid station were recorded. Additional questions asked about their substance use and referrals that had been made to a general practitioner, dentist, or hospital. Finally, based on the Emergency Severity Index ^[15],^[16], each health-related incident was categorized as medical, traumatic, psychological, or miscellaneous, and each incident was designated as minor, moderate (defined as requiring professional medical care within six hours), or severe (defined as life-threatening and needing immediate professional medical care).

In the present observational study, data were collected prospectively and anonymously. According to Dutch regulations, neither medical nor ethical approval was needed to conduct the study. The study was not supported financially in any way. The data were obtained from files maintained by Educare, a nonprofit organization that provides first-aid assistance at large-scale events. The Educare Board of Directors consented to our using the data for scientific purposes.

From 1997 to 2008, 3,793,500 visitors attended 249 rave parties. Most (70%) of the raves occurred at night. Many (N = 27,897; 0.7% of all visitors) of the people visiting a first-aid station presented with complaints that needed some form of medical attention. The mean age of all people visiting first-aid stations was 22.3 years (SD = 5.4), but the age of the visitors increased significantly from 18.7 years in 1997 to 24.0 years in 2008 (r = .245, p<.01). Visitors seeking help at first-aid stations were approximately equally divided between males (52.4%) and females (47.0%).

Across the 12 years, a total of 10,100 people (36.2% of those seeking first aid), representing 0.3% of all rave party visitors, experienced a substance-related incident. The incidents were medical (80%), traumatic (9%), psychological (4%), or miscellaneous (7%). The median overall length of stay at a first aid station was 10 minutes, but it was 20 minutes for substance-using visitors and 5 minutes for nonsubstance-using visitors—a difference that is statistically significant (p<.001) (Table 1).

Most (n = 6912, 64.4%) of the substance-using visitors reported using only one substance, which was usually ecstasy (n = 3308, 32.8%) or alcohol (n = 2296, 22.7%), but a substantial proportion (n = 2554, 25.3%) reported using two substances simultaneously. The most commonly reported combined use was ecstasy with alcohol (n = 1129, 11.2%) (Table 2).

The most common substance-related health problem was a general feeling of being unwell/fainting, which was associated with the use of all substances. Additional minor health-related problems were associated with the different substances. Using amphetamines was associated with having cramps (OR = 6.9); cocaine, with having a high body temperature (>37.5°C) (OR = 29.5) or palpitations (OR = 6.5); and GHB, with altered consciousness (OR = 32.7) (Table 3). Although ecstasy is a stimulant, the combined use of ecstasy and GHB was associated with having a subnormal body temperature (OR = 5.6). The combined use of ecstasy and amphetamines were associated with having psychotic delusions (OR = 9.7), high body temperature (OR = 5.5), cramps (OR = 4.2), palpitations (OR = 3.4), or a stomachache (OR = 2.8). The highest odds ratios were found for the association between altered consciousness and GHB/ecstasy use (OR = 26.2) and GHB/alcohol use (OR = 25.3) (Table 4).

The number of rave-party visitors who sought first aid fluctuated during the 12 years of the study. Between 1997 and 2000, 7,136 people (1.0% of the visitors) needed first aid. Between 2001 and 2004, the number rose to 13,755 (0.8% of the visitors). From 2005 to 2008, 7,006 visitors sought first aid. Across the 12 years, a total of 515 cases were considered serious (i.e., professional medical care was required; Category 1 and 2 of the Severity Index ^[15]), and 262 of these were admitted to a hospital emergency room. First aid stations, however, were mostly often visited by people with no substance-related health complaint. Among those who did use substances, the risk of a serious incident was highest among ecstasy users in the period 1997–2000 (0.21), but this risk decreased to 0.06 in 2005–2008. For alcohol users, the risk was 0.06 during 1997–2000, but it increased to 0.09 in 2001–2004 and 2005–2008 (Table 5). In 2001–2004, the relative risk of having a cocaine-related incident was 21.0. The largest number of serious incidents occurred with GHB use (N = 55), with relative risk of 31.9 between 2001–2004 and 48.9 between 2005–2008 (Table 5). Serious incidents also occurred in these periods with GHB/alcohol use (N = 32; relative risk = 41.4 and 50.5) and GHB/ecstasy use (N = 47, relative risk = 44.1 and 44.8) (Table 6). The combined use of alcohol and cannabis was not associated with having a problem. On the whole, the relative risk of having a serious incident was higher among substance-using visitors needing first aid compared to those who were not using a substance (Tables 5–6). Finally, all severe incidents (life-threatening, Category 1 of the Severity Index ^[15], N = 16) were substance-related; they included four cases of excited delirium, and three each of circulatory insufficiency, respiratory insufficiency, hyperthermia, and severe trauma.

Approximately one-third of all rave-party visitors who sought first aid reported having a substance-related problem. Visitors with substance-related problems stayed longer at first aid stations than those without a substance-use problem. Altogether, 515 of 10,100 substance-related incidents were classified as serious, and 16 of these were life-threatening. Most substance-related incidents were associated with ecstasy or alcohol use or both. It is noteworthy, however, that in the Netherlands alcohol use is relatively common, but ecstasy use is not. It is possible that the willingness of rave-party visitors to present themselves at a first aid station with health-related complaints was related to the drug that they used. For example, ecstasy users' ^[9] need for social contact might have prompted them to seek assistance with minor health-related problems more readily than users of other substances. Additionally, readiness to report one's substance use might have varied according to the social acceptability of using particular illicit drugs.

Unlike what most other recent studies from various countries have found ^[17]–^[24], the occurrence of acute substance-related health problems found in this study was relatively infrequent and the problems were not severe. From their systematic review of the harmful effects of ecstasy use, Rogers et al. concluded that this drug rarely causes death ^[25], and Chinet et al. reported that party-goers who use drugs appeared to be particularly receptive to harm-reduction measures ^[26]. It might be concluded, therefore, that harm and risk reduction as practiced in the Netherlands is effective ^[7],^[8]. It should also be noted that the Dutch generally use drugs in moderation, and they avoid using highly risky substances, such as methamphetamine, which are used in many other countries ^[27]–^[34].

In the current research, no evidence was found for life-threatening, acute effects of GHB. Nevertheless, professional medical care is often required after GHB use and the syndrome that can occur (altered consciousness, vomiting, and subnormal body temperature) can be dangerous. Health education should focus on these secondary effects in addition to the primary effects.

Questions remain about whether the relatively low rate of severe incidents that occurred was related to the open nature and legal status of rave parties in the Netherlands. It would, therefore, be important to replicate this study in other countries. To our knowledge, there is no other published research on substance-related incidents that occur during large-scale events. It would be worthwhile for future research to focus on the causes of these incidents ^[21],^[35]–^[45]. Finally, we recommend that future research also address the secondary factors related to substance-related incidents and the mechanisms involved in them, such as GHB-related airway threats and hypothermia, ecstasy-related hyponatremia, excited delirium, and the serotonin syndrome.

Competing Interests: The authors have declared that no competing interests exist.

Funding: This study is not supported financially by any means. Data are obtained from report files of Educare a non-profit foundation, which provides first aid at large-scaled events. The board of Educare consented in using data for scientific research.

The writers would like to thank all staff members of Educare for their dedication, accuracy, loyalty and contribution to this study. Special thanks to Ludger van Dijk for the statistic support and Attie van der Meulen, Loes Greiner and Marga Witter for always being there.