Table 1

Concussion assessment and outcome measurements among rugby players in the included studies

Ref.Study designMethod of assessing concussion and its definitionMeasurement of outcome(s)Prevalence of outcomeInternal comparisonBetween-sport comparisonExternal comparison
McMillan TM et al, 201732 Cross-sectional with external comparison group (‘population’ controls)

  • Self-reported

  • Definition of concussion: a blow or injury to your head where you may or may not have lost consciousness and then had symptoms such as dizziness, blurred vision, nausea, vomiting, headache, poor concentration. It might be that symptoms were not noticeable straight away but you may have noticed them later or have had ‘gaps’ in your memory for the game that were unusual or you might have remembered little at all about the game

Prevalence of concussion among retired international rugby players: 92%
Mean (SD) number of concussions: 13.9 (18.9)

  • Neurocognitive tests

  • Cognitive function assessed by MoCA 36

  • Anxiety and depression

  • Quality of life

  • Allostatic load

  • Alcohol use

 Prevalence of cognitive impairment defined as M0CA<26: 9/52 (17%)

  • No differences in terms of cognition, among players, according to the number of concussions (no repeat concussion, 0–1; moderate, 2–9 and high 10+)

  • Players performed worse on a test of verbal learning and of fine motor coordination of the dominant hand

  • Prevalence of cognitive decline 17% among former players and 3% among controls (p=0.087)

Hume et al, 201731 Cross-sectional with between sports (community rugby players and non-contact sportspeople) and external comparison group (US norms)

  • Self-reported by online questionnaire

  • Definition of concussion: ‘Concussion was defined as being a blow to the head followed by a variety of symptoms (loss of consciousness, headache, dizziness, loss of balance, blurred vision, ‘seeing stars’, feeling in a fog or slowed down, memory problems, poor concentration, nausea or throwing up)”

Elite rugby players: Prevalence of concussion: 85%
Mean concussions: 3.5±2.0
Community rugby players: Prevalence of concussion: 77%
Mean concussions: 2.9±2.2

  • Neurocognitive tests

  • Former players (including elite rugby, community rugby and non-contact sports) who recalled one or more concussions had worse scores on cognitive flexibility, executive functioning, and complex attention than players who did not recall experiencing a concussion

  • The elite-rugby group performed worse on tests of complex attention, processing speed, executive functioning, and cognitive flexibility than the non-contact sport group, and worse than the community-rugby group on complex attention

  • Compared with US norms, all three former player groups performed worse on verbal memory and reaction time; rugby groups performed worse on complex attention, processing speed, cognitive flexibility and executive functioning

  • Elite rugby group performed better in relation to motor speed than US norms

Decq et al. 201627 Cross-sectional with a between sports comparison group (high-level retired sportspeople)

  • Self-reported by questionnaire.

  • Definition of concussion not provided

Prevalence of concussion among rugby players: 77%
Mean concussions: 3.1 (SD 5.0)
Median concussions: 2 (IQR 1–3)
Mean concussions with loss of consciousness: 1.5 (2.7)
Mean concussions with loss of memory: 0.9 (SD 1.3)

  • Cognitive function assessed by TICSm 37

  • Depressive disorders (PHQ-9 score)

  • Fluency disorders (Isaacs Set Test)

  • Headache severity (HIT-6 score)

 Prevalence of cognitive impairment defined as TICS-m ≤30: 57%

  • No association between concussion and cognitive function among rugby players and other athletes together

  • Mild cognitive disorder (TICS ≤30) prevalence: 57% among rugby players and 40% among other sports (univariate p=0.005)

  • Mean TICS score 30. (SD 3.5) among rugby players and 31.3 (3.6) among other sports (univariate p=0.007)

  • PHQ-9 Patient Health Questionnaire; Hit-6, Headache Impact Test; IQR, inter quartile range; IQR, Inter-quartile range; MoCA, Montreal Cognitive Assessment; SD, Standard deviation; TICSm, Modified Telephone Interview for Cognitive Status.