Discussion

The range and number of Rugby-7s and Rugby-15s tournaments included in this study should mean that the results are representative of elite rugby, which allows the conclusions from the study to be generalised. The incidences of concussion recorded in the Rugby-15s competitions (3.3–5.4) were similar to those reported in previous studies (2.6–7.8)12–16; however, the incidence of concussion recorded in the Rugby-7s tournaments was four times higher than that reported previously.17 The higher incidence of concussion recorded in the present Rugby-7s study may reflect a real increase in the period since the previous study or may merely provide a better estimate of the true value as only two concussions were recorded in the earlier study. The incidence of concussion in Rugby-15s was lower than the incidence reported for American football (18.2),22 and rugby league (9.8),23 but higher than that reported in ice hockey (1.8)24: for Rugby-7s, the incidence was lower than that for American football, similar to rugby league and higher than ice hockey.

The overall incidence of concussion in Rugby-7s was higher than that observed in Rugby-15s; however, the incidence of concussion in the first of the paired Rugby-7s tournaments was similar to that observed in Rugby-15s: the overall difference therefore resulted from the higher incidence in the second of the paired tournaments. The higher incidence in the second tournaments may result from cumulative player fatigue resulting from playing two tournaments within 10 days; however, there was no indication that fatigue was a risk factor within individual games, as the proportions of concussions sustained in the first and second halves of games were similar,25 or within tournaments, as fewer concussions were sustained on day 2/3 than on day 1. It is possible that the difference could be linked to the logistical arrangements for the paired tournaments in the Sevens World Series. Most Rugby-7s teams travel with a squad of 12 players; hence, because of the short time period (5–7 days) between the last match in the first tournament and the first match in the second tournament, it may sometimes be difficult for teams to replace injured players in time for the start of the second tournament. Additionally, any player declared with a concussion injury at the end of the first tournament of a back-to-back pair of tournaments would most likely have to miss the second tournament because the medical team would not be able to predict whether a concussed player would recover within the minimum 6 days required. It is possible therefore that mild concussions sustained in the first of the paired tournaments were undeclared by some players and/or medical teams. Players sustaining a concussion in the second of the paired tournaments would not be affected in the same way, as pairs of tournaments take place every 1–2 months, which provides sufficient time for most players to recover from concussions sustained in a second tournament.

Although there were no significant differences between the severities of concussion sustained by backs and forwards in either Rugby-7s or Rugby-15s, the overall mean and median severities of concussions sustained by players in Rugby-7s were significantly greater than those sustained in Rugby-15s. However, the severity of injuries sustained in the first of the paired Rugby-7s tournaments were similar to those sustained in Rugby-15s; the difference therefore results from the severity of Rugby-7s concussions sustained in the second of the paired tournaments. It is not apparent whether this difference is a real effect or whether it simply reflects the extended time available between each set of paired tournaments, which enables physicians and physiotherapists to adopt a more conservative rehabilitation process for concussed players.

The proportion of players returning to training/match play within 10 days (Rugby-7s: 38%; Rugby-15s: 72%) was lower than the 80–90% value quoted in the fourth International Conference on Concussion in Sport statement6; this may indicate that more conservative return-to-play practices are adopted in rugby compared to other sports. It is also apparent from figure 1 that the proportion of players (Rugby-7s: 18%; Rugby-15s: 48%) returning to match play in less than the current IRB guideline minimum concussion recovery time of 6 days (when under the supervision of a medical practitioner) is significant and this warrants further investigation. The median severities of concussion observed in this study of rugby union were similar to values reported previously for professional ice hockey (median severity: 6 days),24 but very much higher than values reported for American football (mean: 2–5 days; median: 0–1 days),22 although these values seem surprisingly low.

Players sustaining a concussion in Rugby-7s were more likely to be removed immediately from the pitch than they were in Rugby-15s. However, this trend is most likely a reflection of the format of the game and the relative impact on team performance of physicians taking match-time to assess a player for concussion in a team of 7 players during a 14 min Rugby-7s game compared to the impact in a team of 15 players during an 80 min Rugby-15s game. The proportions of players sustaining a concussion who were not removed immediately from play are high in both game formats and until questions about possible links between concussion and potential long-term sequelae have been answered,2–6 this proportion should be reduced.

The only significant differences in the anthropometric data of concussed players compared to the sample population were that concussed players were older; this may be related to the fact that older players are more likely to have sustained a previous concussion, which it is claimed is a risk factor for further concussions.2–6 In general, Rugby-7s and Rugby-15s players were most likely to sustain concussions when tackling or in collisions although, for Rugby-7s backs, the second most common cause was being-tackled. This shows similarities and differences to the causes of concussion in other full-contact sports, which supports the argument for obtaining sport-specific information about the nature and causes of concussion. In American football,22 tackling (29%), being tackled (27.5%), being blocked (16.2%) and blocking (16%) were the most common activities leading to concussion; whereas, in rugby league head-high tackles (39.5%) and head contact with the ground (34.9%) were identified as the major causes.23 The results from the present study indicate that the major causes of concussion in rugby union are controllable, which provides scope for developing and communicating effective injury prevention strategies. The IRB Rugby Ready training programme teaches players the correct tackling technique, which includes ensuring that players have their head in the correct position to minimise the risk of sustaining a concussion. Second, deliberate collisions are not allowed within the Laws of the Game26; Law 10.4(g) states that charging or knocking down a player without trying to grasp the player constitutes dangerous play. It has been reported previously that 97% of collision events in Rugby-15s go unpunished26; the potential for reducing the role of collisions in concussion injuries is therefore large but match referees must play a major part by rigorously enforcing the Laws of the Game and by imposing the appropriate penalties on players, as this should act as a strong deterrent.

The data, conclusions and generalisations reported in this study relate specifically to the men's elite, professional game of rugby union (Rugby-7s and Rugby-15s). It is recognised that the overall incidence of injury and the incidence of concussion are significantly lower at the men's and women's community level of play than the values reported in this study. Additionally, the recommended pitch-side and postgame protocols for the management of concussion at the community level are quite different from those at the professional level of the game. For these reasons, the conclusions reached from this study cannot and should not be generalised to the community level of play in rugby union.

This study has confirmed the level of concussion in elite/professional Rugby-15s across a range of competitions and established for the first time the level of concussion in elite/professional Rugby-7s. The results presented highlight a number of areas of the game where there is the potential for reducing the risk of concussion in rugby. First, implement a pitch-side concussion assessment protocol (consisting of appropriate assessment tools together with guidance on their application and time for their implementation) to aid the decision-making of physicians in order to increase the proportion of concussed players being removed immediately from the pitch. Second, determine the reasons why a high proportion of players return to play, following a concussion, in less than the IRB recommended 6-day recovery period. Third, work with referees to minimise the consequences of collisions. Fourth, improve players’ tackle technique and increase players’ awareness of the connection between poor tackle technique and concussion. Fifth, examine the forces involved in tackles and collisions to identify the biomechanics of the concussion mechanism and to identify potential mitigation strategies. Sixth, establish the reasons for the higher incidence of concussion during the Rugby-7s Rugby World Series and, if necessary, examine the logistics associated with paired tournaments in the Series.