• RFU report shows rise in top-flight tackles and involvements since changes • ‘A full season of data will be needed to make a full analysis’ - World Rugby

World Rugby says it is too early to draw a link between the spate of injuries sustained in the Premiership this season and the new global law changes, following research by the Rugby Football Union that suggests otherwise.

An RFU “game trends summary data” report found an increase in the average number of tackles (11.4%), “involvements” (8.8%) and rucks (11.9%) per match, as well as ball-in-play time in the first five weeks of the season, while the number of collisions per match is also up.

Jamie Roberts, the Harlequins and Wales centre and a qualified doctor, is among those to suggest that the increases are as a result of the law changes introduced in the northern hemisphere in August, designed to make the game “simpler to play and referee, as well as further promoting player welfare”, and are contributing to the glut of recent injuries that has left a number of Premiership squads decimated. Billy Vunipola and Manu Tuilagi are among the high-profile players out of action until next year.

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Nigel Melville, the RFU’s director of professional rugby who commissioned the report, told the Telegraph: “We do have to look at the consequences. You can get something right and create a problem somewhere else and that is always the challenge when you change laws. What we are seeing is a reduction for the contest for the ball, more involvements, tackles because more people are available in the defensive line which makes it more attritional.”

However, World Rugby highlighted the danger of drawing conclusions based on anecdotal feedback from a handful of games in one league. The world governing body also questioned whether there has been a global rise in the number of injuries and suggested the increase in tackles, collisions and “involvements” is part of a trend because of changes in player and coach behaviour in recent years, rather than an immediate consequence of the law changes.

A World Rugby spokesperson told the Guardian: “Player welfare is rugby’s primary consideration and all law amendments are made with this as the central consideration and are only implemented globally after a process of robust analysis of closed trials.

“These comprehensive closed trials do not support any adverse player welfare trends and it is too early to draw any robust and reliable conclusions from a handful of rounds in one competition. This is especially pertinent when trying to determine possible explanations for injury trends, because there are a multitude of factors that need to be considered such as training load, the player’s injury profile and so on.

“We know that injury rates fluctuate, but the general trend is that there is no global increase. A full season of global like-for-like data will be needed to make a full analysis.”

The 11 global law changes were introduced to the northern hemisphere at the start of August and are still in the trial phase. They include three changes to scrum and three to the ruck/tackle, which is said to have led to defending teams committing fewer players to the breakdown, thereby limiting space and increasing the number of collisions.

World Rugby’s law review group, of which Melville is a part, will review the amendments at the end of domestic season and make a recommendation as to whether they become permanent – as is the case with any law trials.

The amendments were approved by the World Rugby council last November, following closed trials at lower-profile competitions such as the Junior World Championship. They will be in force during the autumn Tests, something the referee Wayne Barnes believes will give the home nations an advantage over their southern hemisphere rivals – as well as the Six Nations.

A World Rugby statement read: “[The] comprehensive data, along with the game analysis data and participant feedback will be considered by the Law Review Group to inform decisions as to whether any law amendment trial goes forward into law.”

The RFU, meanwhile, has confirmed it will pass its findings on to World Rugby. A spokeswoman told the Guardian: “As the governing body in England, we have a responsibility to look at all elements of the game. We try and take an evidence-based view so we are looking at the data available and will pass our early interpretations of it on to World Rugby in the usual way.”

The England Professional Rugby Injury Surveillance Project Steering Group – a joint venture between the RFU and the Premiership – was due to meet this month to assess injuries sustained last season as well as in the opening rounds of this campaign. The group will publish its annual injury audit in the new year.