Sports injury is common, and subsequent pain is a normal physiological accompaniment of such injury. Pain is defined as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.”1 Furthermore, pain can reflect the mechanism of injury and be influenced by biopsychosocial factors. The experience of pain is shaped by neurophysiological, cognitive, affective, social, and environmental influences. Given these complexities and the absence of clear clinical guidelines, pain management strategies vary internationally and often do not reflect an understanding of the cause and type of pain experienced by athletes.
Elite athletes, such as professional athletes and athletes competing internationally, likely experience pain and pain treatment differently than people undertaking general exercise.2–4 Elite athletes may use oral, injectable, and transdermal nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, opioids, injectable and transdermal anesthetics, as well as cannabinoids, antidepressants, anxiolytics, muscle relaxants, and anticonvulsants.5–8 Furthermore, because of their unique training and competition regimens, and their access to specialized medical support, elite athletes may be more likely to use multiple agents, receive analgesics from multiple sources, or use analgesics to prevent pain.5,9–11 However, efforts to prevent or manage pain solely with medications can increase risk of adverse effects while failing to resolve underlying pain conditions.12–15 In addition, some substances used for pain are listed on the World Anti-Doping Agency (WADA) List of Prohibited Substances and Methods, including some opioid analgesics and cannabinoids.15
Despite indications that medication use to relieve and prevent pain is widespread among elite athletes,5,9,11,16–18 there has never been a comprehensive undertaking to identify the usage frequency and effect of pain medications among elite athletes. A systematic literature review focused on elite athletes can provide a foundation for clearer, more consistent, and evidence-based recommendations regarding athletes' medication use, healthcare professionals' medication prescribing, and anti-doping policy. Therefore, the objective of this study was to conduct a systematic literature review to identify the usage frequency and effect of analgesic pain management strategies in elite athletes. This review also served as a foundation for some of the key questions examined at the International Olympic Committee (IOC) 2016 Consensus Meeting on Pain Management in Elite Athletes.19
We followed the PRISMA guidelines20 to conduct a systematic review of the peer-reviewed literature to examine what is currently known about medication for pain management in elite athletes. Our search joined 3 general search concepts: (1) pain or analgesic treatment modalities, (2) athlete/sport, and (3) elite. With this, we aimed to retrieve literature related to the use and effect of medications for pain or painful injuries in an elite athlete population. Between February 2 and 14, 2017, we searched 6 literature databases, Ovid/Medline, SPORTDiscus, CINAHL, Embase, Cochrane Library, and Scopus (see Appendix, Supplemental Digital Content 1,http://links.lww.com/JSM/A178 for detailed search strategy). This search provided an update to a search we conducted in November 2015, which served as a reference to the IOC Consensus Meeting on Pain Management in Elite Athletes. We searched each database using a controlled vocabulary and keywords that represented the 3 general search concepts mentioned above (see Appendix, Supplemental Digital Content 1,http://links.lww.com/JSM/A178 for full syntax). We restricted our searches to English language and human studies. We did not restrict to a specific date range. In addition to the primary searches, we examined supplemental sources for qualifying articles. These sources included the reference lists of systematic review articles returned by our searches.
After retrieving article results for each database and supplemental sources, we conducted an initial review of titles and abstracts to identify relevant articles. We used a PICO (population, intervention, comparison, outcome) approach as a starting point for our inclusion criteria, although our review is broader and not all included studies simply map to each PICO criterion.21 In particular, our relevant population was elite athletes; relevant interventions were analgesics or other medications used for pain; relevant comparisons were any; and relevant outcomes were any outcomes related to prevention or treatment of pain or painful injuries. We included empirical studies involving elite (ie, Olympic, Paralympic, professional, collegiate, or other elite) athletes, where at least one of the article's foci was on the use, efficacy, or effectiveness of medications used for pain or painful injuries. Studies involving “other elite” athletes were those identified by the authors using keywords such as “elite” or “competitive.” Such studies often involved nationally recognized athletes, such as those supported by national Olympic training programs or youth national teams. However, we also included a small number of studies where the authors simply identified study participants as competitive and article context suggested involvement of elite athletes. We excluded studies that were not empirical, commentaries, nonsystematic literature reviews, and studies that included fewer than 10 elite athlete participants. We also excluded articles focused on pain medications that are no longer used in humans.
After the initial title and abstract review, we examined the full text of remaining articles to determine final inclusion and to code each article for relevant features. Three reviewers first coded a 20% subsample of the total articles and discussed differences to increase subsequent consistency in coding. The remaining articles were each coded by a single reviewer. Then, the 3 coders met as a group to review final article inclusion and discuss any uncertainties that arose during individual coding. When coding the articles, we extracted the publication year, study design, risks of bias, sample size, population (including sport, athlete sex, and athlete country), interventions, type of pain/injury, location of pain/injury, duration of pain, study outcomes, and authors' interpretation of the intervention effect (desirable, undesirable, none, unknown, or not applicable). We synthesized results by generating summary statistics and qualitative interpretations of the coding results and in-depth article reading.
Our searches found 5321 total articles, and 4700 after duplicates were removed (Figure 1). We excluded 4589 articles after reviewing titles and abstracts. We most commonly excluded articles because they were not empirical or because they focused on nonathlete or nonelite athlete populations. Next, we reviewed the full text of the remaining 111 articles and excluded 49 of those. We excluded articles in this final stage because further analysis determined that they involved nonelite athletes, were nonsystematic reviews, were not empirical, did not involve pain medications currently used in humans, or were clearly duplicative of articles or data already included. Finally, we included 8 other qualifying articles from other sources. Together, this process resulted in a final set of 70 articles for analysis.5,8–11,16–18,22–50,51–83
Overview of Studies
The 70 articles were published between 1975 and 2016. In 20 articles, the athletes studied originated from multiple countries. Fourteen articles involved athletes from only the United States of America, the most from a single country. Also, multiple studies involved athletes from Argentina, Australia, England, Finland, Norway, Germany, and Italy, with other countries represented in a single article only. Thirty-two studies involved multiple sports. Sixteen of the single-sport studies involved football (soccer). Other sports found in multiple articles include American football, basketball, rugby, cycling, hockey, track and field, volleyball, handball, and judo. In terms of athlete level, 25 articles involved professional athletes or a mix of professional and other elite athletes. Nine articles involved collegiate or a mix of collegiate and other elite athletes. Eleven articles involved Olympic or a mix of Olympic and other elite athletes. One article focused solely on Paralympic athletes. The remaining articles focused on other elite athletes. Athlete sex was sometimes not specified and could not be clearly inferred from the information presented in 15 articles. However, 23 articles involved only male athletes, and 33 articles clearly involved a mix of male and female athletes.
Studies of Medication Use
The largest group of included articles (n = 45) reported frequency of medication use by athletes across a range of sports. Often, these studies described analyses of doping control forms, therapeutic use exemptions, pharmacy services, or other reports collected during major sporting events, such as the Olympic Games,10,22,27–29,40,77 Paralympic Games,22,76 Pan-American Games,30,81 Asian Games,57 and Fédération Internationale de Football Association (FIFA) tournaments.11,17,18,26,58,75,80 Other studies surveyed collegiate athletes.38,46,64,74,82 In addition, some studies provided estimates through analysis of drug chemistry results (in- or out-of-competition).26–28,32,57,65
Oral or Nonspecific Route Nonsteroidal Anti-inflammatory Drugs
Nonsteroidal anti-inflammatory drugs are the most frequently studied and reported to be the most frequently used pain medication. Table 1 provides an overview of 25 studies that report oral (or nonspecific route) NSAID use rates. We were challenged to compare frequencies across all articles because studies reported estimates using different techniques and over different periods, such as in the past 12 months, in season, in the past 7 days, or during a given competition. Also, articles varied with respect to the mix of sports reported on and in the source of the medication data, such as physician-prescribed, athlete self-report, laboratory testing, or pharmacy records. On one hand, some articles presented relatively low prevalence of NSAID use, including 2.4% of urine samples containing traces of NSAIDs at the 1988 Olympic Winter Games,28 6.7% of Finnish Olympic athletes prescribed NSAIDs in the past 7 days,22 9.8% of Paralympic athletes who declared NSAID use on doping control forms during the Athens 2004 Games,76 and 11.1% of Olympic athletes who declared NSAID use on the doping control forms during the Athens 2004 Games.77 On the other hand, some articles described relatively high rates of use, including 100% use in nontraumatic injuries suffered during an international cycling race (n = 16),83 93% use in the past year among Italian professional football players,69 over 50% use during the course of an international football tournament,11,17,18,75,80 and 50% use among collegiate American football players over the course of a season.38 Studies consistently suggested that NSAID use rates are concerning for myriad reasons, including concurrent use of multiple NSAIDs, multiple routes of administration, higher than the manufacturer's recommended dosing, use for prophylaxis of pain, limited evidence-based clinical guidance, adverse effects, and limited evidence regarding effects on injury healing.5,10,11,17,29,38,40,58 However, some male former athletes may actually be less likely to use NSAIDs when compared with age-matched controls.43 And, there is some indication that the frequency of NSAID use decreased during the 2014 FIFA Men's Football World Cup compared with previous years' tournaments.80
Injectable Pain Medications
Compared with oral NSAID use, fewer studies reported on injectable NSAID use. Among Paralympic athletes, 9.8% reported using NSAIDs on the doping control forms, with 11.6% of those administered through injection.76 Also, 93% of National Football League (NFL) physicians in the USA reported administering injectable ketorolac as often as once per week during the 2000 season, with 21% of teams reporting an adverse experience.71 Similarly, across many sports, 79% of American sports medicine physicians reported administering injectable ketorolac to collegiate athletes and 43% reported administering to professional athletes, with 12% reporting an adverse reaction.8 Finally, an estimated 31% of football players received NSAID injections before matches during the 1996 African National Cup.9
Some studies reported injectable anesthetic and/or corticosteroid use. However, like with NSAIDs, the approach to measuring and reporting of this practice varied. For example, injectable anesthetics and injectable corticosteroid use were sometimes combined and reported in a single use estimate. In other studies, injectable and oral corticosteroids were combined and reported in a single use estimate. A study of Paralympic athletes reported injectable corticosteroid use in 0.1% of athletes and injectable anesthetic use in 1.9% of athletes.76 An estimated 13.5% of hamstring injuries in NFL players are treated with injectable corticosteroids.44 During the 2014 FIFA Men's Football World Cup, team physicians reported that 2.6% of athletes used injectable anesthetics and 3.1% used intraarticular or periarticular injectable corticosteroids.80 Similarly, between 2.2% and 5.7% of male athletes used either injectable anesthetics or injectable corticosteroids at each of the FIFA Futsal World Cup tournaments between 2002 and 2012.58
Opioid Analgesic Medications
Most studies that asked athletes about, or tested samples for, opioids reported use rates below 1% of athletes.26,28,32,35,57,58,65,76,79 A study of pharmacy records from team South Africa during the Athens 2004 Olympic Games found an average of only 1.54 tablets of opioid-containing analgesics (eg, paracetamol/ibuprofen/codeine) were dispensed per athlete.10 Similarly, few athletes report being offered or knowing someone who has used opioids.23 However, one small study reported tramadol use in 3.3% of 30 elite cyclists over the previous 3 months.45 Also, 5.6% of Nigerian professional athletes reported using codeine at some point in the past.52
Other Medications Used for Pain
Reported rates of non-NSAID oral analgesic medications ranged from 0.4% of players at the 2007 Under-20 World Cup11 to 20% among elite Italian cyclists in the previous 3 months.45 Often, such medication use was reported simply as “analgesic” rather than specifying what types of non-NSAID medications, such as paracetamol. An analysis of over 18 000 doping control forms between 2002 and 2005 found that less than 1% of athletes had used anesthetics, such as lidocaine, in the past 3 days.79 Similarly, 1.6% of urine samples analyzed during the 1988 Olympic Winter Games tested positive for lidocaine.28
Similar to NSAIDs, estimates of corticosteroid use varied, partially due to different approaches to measurement. Rates of any corticosteroid use (route of administration not specified further) in the past 3 days as assessed by doping control forms in the mid 2000s includes estimates between 1%67 and 6.2% to 9.2%.79 Corticosteroid use among elite cyclists was estimated at 15.8%.34 Surveys of physicians about oral corticosteroids, either in or out of competition, found that 83.9% of team physicians prescribe to NFL players78 and 32% of physicians prescribe to collegiate athletes.46 Finally, 3 other studies of collegiate athletes surveyed use of all nonprescription over-the-counter medications combined, including NSAIDs, paracetamol, and others.64,74,82 These studies found use of over-the-counter analgesic medications by 58% to 73% of athletes. These studies also reported that athletes lacked awareness about adverse effects,74 had significant external influence to use pain medications, and frequently misused pain medications,74,82 especially collegiate American football players.64
Studies Assessing Effects of Medications
Randomized Controlled Trials
We reviewed 8 randomized controlled trials (RCTs), all but one of which was published in 1990 or earlier and had sample sizes of 13 to 60 athletes (Table 2). Five of the 8 RCTs compared the effect of 2 different oral NSAIDs on acute pain when treating various injuries.33,48–50,61 Each study included pain as a primary outcome, measured by self-report numeric rating or visual analog scale. Secondary outcomes included swelling,48 return to sport,49 and physical function.49 These studies all found differences in the efficacy of different NSAIDs. Flurbiprofen was more efficacious than aspirin in terms of pain reduction and return to play related to acute lower-limb soft tissue injuries.50 Furthermore, piroxicam was more efficacious than tenoxicam33 and naproxen48 in reducing pain from an acute sport-related ligament sprain. Piroxicam was also shown to be more efficacious than ibuprofen in reducing acute pain and increasing active and passive physical function in athletes with sprains, strains, and other soft tissue injuries that had caused functional disability.61 In addition to the RCTs involving oral NSAIDs, one study of collegiate athletes found that diflunisal, a salicylic acid derivate, was equally efficacious in reducing pain, tenderness, and swelling due to acute injury as paracetamol combined with codeine.41
The most recent RCT, from 2006, examined elite athletes with chronic patellar tendinopathy and found sclerosing injections of polidocanol to be more effective in improving pain scores and function assessments than lidocaine with epinephrine injections.36 Finally, one RCT compared the effect of naloxone versus placebo in noninjured athletes.66 The study found weak evidence to suggest that naloxone may reduce affective components of pain but not sensory, evaluative, supplemental, or overall pain intensity.84
Twelve of 14 observational studies evaluated the effects of non-NSAID injectable therapies, which included corticosteroid injections,39,42,44,68 injectable or local anesthetics,51,53,54,62 and, in chronic situations, regenerative dextrose injections,72,73 and sclerosing injections24,37 (Table 3). These studies focused on groin pain,39,51,62,72,73 hamstring injury,44,68 lumbar disk herniation,42 patellar tendinopathy,24,37 or a mix of injuries and pain.53,54 Four studies reported on acute pain or injury.39,42,53,62 Four studies reported on either chronic pain or chronic and subacute pain combined.24,68,72,73 Four studies were nonspecific about pain chronicity.37,44,51,54 The majority of the studies concluded that there were positive effects of the primary therapy on reduction of pain or related outcomes. Studies finding negative or null results often suggested the need to evaluate the risks and benefits of the therapies on a case-by-case basis. However, in terms of study design, none of the studies of injectable medications used a control group, which may bias their conclusions. Furthermore, these studies had a mean sample size of 55. Seven of 12 studies had samples of less than 30, including several case series. The 2 largest studies (N ≥ 100 treated injuries) each retrospectively examined the effects, including complications, associated with injectable therapies for analgesia. In one study of 1023 local anesthetic injections recorded in a cohort of 100 players, 73% of athletes perceived the therapy as helpful. But, 22% thought that the injury took longer than expected to recover and 6% thought the injury worsened.54 The other study examined 268 injuries treated with anesthetics (221 injection and 47 topical). Among these, there were 11 minor and 6 major complications.53
In addition to the injectable analgesic therapy observational studies, one study examined 28 Australian football players who received intranasal sumatriptan for moderate-to-severe acute headaches (both migraine and nonmigraine). The study found that symptoms resolved or became mild in 86% of headaches within 2 hours of taking sumatriptan.47 Another qualitative study interviewed 36 breaststroke swimmers about chronic knee pain and concluded that NSAIDs may be useful in reducing symptoms of knee pain.60
Studies of Attitudes Toward Pain Medications
Four studies assessed elite athletes' knowledge of and attitudes toward pain medication use, either in the broader context of drug use in sports23,55,56 or in the context of playing with injuries.59 A survey of 446 Finnish athletes on banned substances found that 13.8% of athletes believed narcotic analgesics have performance-enhancing effects; 1.2% said narcotic analgesics had been offered to them, but only 0.5% claimed to know athletes who used these substances.23 In a series of 11 interviews, elite amateur cyclists described regular use of NSAIDs in combination with caffeine.55 Pan and Baker surveyed collegiate athletes on their attitudes toward 16 banned substances, including morphine. The study found that female athletes, more than male athletes, perceived morphine as having some athletic relevance, functional benefits, and some dysfunctional effects.56 Finally, English professional football players, club doctors, and club physiotherapists all described enormous pressures to avoid missing matches due to injury. They reported that injectable analgesic use was related to guilt over missing matches, fear of losing a roster spot, and desire to reach minimum game appearance thresholds to achieve additional pay.59
We identified and reviewed 70 studies related to pain medications and elite athletes. One important finding was that the majority of the literature describes frequency of pain medication use rather than assessing the effects of pain medications on health-related outcomes. Thus, the majority of the literature directly assessing analgesic use in elite athletes has limited use in directly helping sports healthcare professionals make evidence-based treatment choices relating to pain medications. A second finding was that studies that do assess pain medication efficacy or adverse effects are often several decades old and have unreliable methodologies, including small sample size and lack of control groups, which can contribute to bias in the findings. These weaknesses prevent us from making literature-driven policy or treatment recommendations about pain medication use in elite athletes.
The specific finding with the most empirical support is the widespread use of NSAIDs among elite athletes. Nearly every study that measured use frequency of different pain medications indicated that NSAIDs were the most frequently used medication. In football (soccer) in particular, several studies that include data from several international tournaments report in-tournament oral NSAID use among at least 30% of athletes, and in some tournaments, among more than 50% of athletes. These use rates tend to be much lower than estimates of other pain medication use, including other oral analgesics and injectable NSAIDs, anesthetics, and corticosteroids. These studies do not empirically assess the risks or benefits associated with NSAID use, although studies in general populations and nonelite athletes have identified health risks related to NSAID use.14,85–87 Thus, in the studies we reviewed, the articles' authors frequently question the safety of observed NSAID rates of use. Without specific data, the articles also raise concerns about unsafe patterns of use, such as use of multiple concurrent NSAID use, multiple routes of administration, high dosing, and inappropriate use for pain prophylaxis. Thus, an important area of future study is to develop more rigorous quantitative understanding of the patterns of NSAID use in elite athletes and potential associated health risks.
Varying approaches to estimating analgesic medication use rates made it difficult to make precise comparisons of frequency of use across studies. For example, some studies, such as those relying on doping control data, estimate use based on athlete-reported use in recent days. Other studies survey athletes out of competition and ask about use over longer periods, such as the past year. Still, other studies measured pharmacy dispensing records or physician reports of their prescribing of certain medications to elite athletes. Thus, we were unable to make reliable comparisons about use rates, such as over time, across sports, or between different subpopulations of elite athletes. Future research that aims to more reliably compare use rates should consider adopting previously used questionnaires or other measurement methods. We recognize this is challenging when studies often rely on secondary data. Still, future research would benefit from increased consistency in data collection and approaches to measuring and reporting medication use.
A minority of studies reviewed actually examined outcomes of medication use for pain. Furthermore, the literature contains very few RCTs, the most rigorous of research designs. Of the RCTs found, only one was published in the past 25 years. Perhaps, owing to challenges of recruiting elite athletes, the RCTs also tended to be conducted on small samples. Thus, we question the generalizability of these results to today's elite athletes. The observational studies found tended to be published more recently and to focus on the effects of injectable pain medications. These studies' tended to report positively on the effect of injection therapies in having minimal complications, reducing pain, improving function, and helping athletes to return to play. However, the validity of these results should be interpreted cautiously due to their tendency to be based on small samples and their lack of control groups. Again, although we recognize practical challenges, future research would benefit from more RCTs and more rigorous retrospective research on pain medications and health outcomes. Such research may benefit from developing or using existing research registries, electronic health record data sources, identifying control groups, and using advanced statistical methods to further control for unobserved differences when comparing athletes who received different treatments.
Our findings suggest some sports and athletes that can be targeted with interventions to prevent analgesic misuse or adverse effects. First, several studies reported relatively high levels of NSAID use among football players,11,17,18,69,75,80 and pressure to use medications to return to play.59 Therefore, national and international football organizations might consider increasing education and other interventions to mitigate NSAID risks among their constituent athletes. Second, studies reported relatively high analgesic use among collegiate athletes,8,38,64,74,82 as well as poor awareness and perceived pressure to use medications.64,74,82 As a result, collegiate and younger athletes generally may also be an important group to better educate about safe analgesic use and effective pain management.
One limitation of this study is that it does not reflect research on pain management in nonelite athletes. However, in this study, we chose a more focused approach that considered elite athletes, a distinct group with different needs, pressures, and treatments relative to injury and pain. With this approach, we aimed to summarize evidence that would be most generalizable to elite athletes. A second limitation of this study is the potential for inaccurate article inclusion or exclusion based on the study population (ie, elite or nonelite). To mitigate this limitation and apply a consistent identification approach, we used multiple coders and group discussion to resolve disagreement. Also, given our interest in elite athletes, we applied a conservative standard for inclusion, thereby excluding articles for which the population was unclear. Last, we reviewed many studies that varied in their approach to measuring and reporting medication use frequency. As a consequence, our review was unable to quantitatively summarize medication use frequency across studies. Similarly, we found few studies that focused on medication effects and attitudes toward medication use, and many studies we found had small sample sizes. This also limited our ability to quantitatively summarize previous work.
Existing empirical research does not provide a sufficient body of evidence to guide athletes and healthcare professionals in making analgesic medication treatment decisions. Based on the relatively robust evidence regarding the widespread use of NSAIDs, clinicians and policymakers should carefully assess their current recommendations for NSAID use and adhere to a more unified consensus-based strategy for multidisciplinary pain management in elite athletes. Our hope is that this article and related work will kindle a more rigorous, prospective assessment of various pain management strategies in elite athletes, thus enabling a shift from consensus-based recommendations to evidence-based recommendations.
The authors thank the participants in the 2016 International Olympic Committee Consensus Meeting on Pain Management in Elite Athletes, including Alan Vernec, Richard, Budgett, Masataka Deie, Stanley Herring, Mike McNamee, Lorimer Moseley, Bade Omololu, John Orchard, Andrew Pipe, Babette Pluim, Johan Raeder, Christian Siebert, Torbjorn Soligard, Mike Stewart, Judith Turner, Mark Ware, David Zideman, and Lars Engebretsen, for their input on the development and interpretation of this study. The authors also thank Elaine Skopelja and Sarah Downs from Indiana University for their input and contributions to the design and analysis of this systematic review.
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