Table 2.
Characteristics of included studies
| Reference | Study design | Type of boxing, duration of follow-up, No of bouts (mean unless stated) | Outcome measures used | No of cases | No of controls | Selection of cases and controls | Methods used to control for confounding (when applicable) |
|---|---|---|---|---|---|---|---|
| Porterw1 | Cohort | Club, 9 years, 80 | Psychometric | 20 | 20 | Random | Age, geographical, sex, socioeconomic status |
| Porterw2 | Cohort | Club, 2 years, 50 | Psychometric | 20 | 20 | Random | Age, geographical, sex, socioeconomic status |
| Zetterbergw3 | Controlled before-after | NS, 3 months, 1 | Cerebrospinal fluid biochemistry | 14 | 10 | NS | Age, sex |
| Moriartyw4 | Controlled before-after | Club, 7 days, 1-3 | Psychometric | 85 | 30 | 1 tournament | Age, sex, education |
| Stewartw5 | Case series before-after | Club, 2 years, 0->11 | Psychometric, EEG, Brain evoked potentials | 369 | 0 | Invitation | Before and after (that is, act as own controls) |
| Butlerw6 | Cohort | Club, 2 years, 4 | Psychometric | 86 | 78 | Invitation | Age, sex |
| Haglundw7 | Case-control | Club, NA, 28 (estimate) | CT, MRI | 47 | 50 | Random | Age |
| Braynew8 | Controlled before-after | NS, 2 hours, 1 | Creatine kinase BB | 16 | 16 | Invitation | Age, sex |
| Masterw9 | Controlled before-after | Club, 1 bout, 1 | Psychometric | 38 | 28 | Random | Age, sex, education, weight |
| Heilbronnerw10 | Case series before-after | NS, 5 min, 1 bout | Psychometric | 28 | 0 | Invitation | Before and after (that is, act as own controls) |
| Kempw11 | Case-control | Military, NA, 40 (median) | Psychometric, SPECT | 34 | 34 | Invitation | Age, sex |
| Mureliusw12 | Case-control | Club, NA, 28 (estimate) | Psychometric | 50 | 50 | Random | Age, education, sex |
| Haglundw13 | Case-control | Club, NA, 28 (estimate) | Neurological, Psychometric, Pt MAO | 50 | 50 | Random | Age, education, sex |
| Haglundw14 | Case-control | Club, NA, 28 (estimate) | EEG, brain evoked potentials | 50 | 50 | Random | Age, education, sex |
| Levinw15 | Cohort | Club, 0.5 years, 2-7 | Psychometric, MRI | 2 | 13 | Invitation | Age, sex, education, socioeconomic status |
| Brooksw16 | Case-control | Club, NA, 26 | Psychometric | 29 | 19 | Invitation | Age, sex, education, ethnicity |
| Thomassenw17 | Case-control | Champions, NA, 76 (median) | Psychometric, EEG, neurological | 53 | 53 | Invitation | Age, sex, education, occupation, |
| Holzgrafew18 | Case-series before-after | Top class, 2 months, 1 | MRI | 13 | 0 | Invitation | Before and after (that is, act as own controls) |
| Jedlinskiw19 | Case-control | >100 bouts, NA, 153 | Psychometric, EEG, neurological | 60 | 30 | Invitation | Reported as “characterologic” |
| Rodriguezw20 | Case series | NS, NA, NS | Regional cerebral blood flow | 7 | 0 | invitation | NA |
| McLatchiew21 | Case series | Club, NA, 4-200 | Psychometric, CT, EEG, neurological | 20 | 0 | Invitation | NA |
| Rossw22 | Case series | Club, NA, 13-150 | CT, EEG, neurological | 13 | 0 | Invitation | NA |
| Jordanw23 | Case series | NS, NA, NS | MRI, CT | 4 | 0 | Selected* | NA |
| Legwoldw24 | Case series | Military, NA, 4 | Neurological | 7000 | 0 | Compulsory | NA |
| Jordanw25 | Case series | Knockouts, NS, 13 | MRI, neurological | 9 | 0 | Selected | NA |
| Cassonw26 | Case series | Club, NA, 0-80 | Psychometric, CT, EEG, neurological | 5 | 0 | Invitation | NA |
| Kastew27 | Case series | National, NA, 129 | Psychometric, CT, EEG, neurological | 8 | 0 | Invitation | NA |
| Corsellisw28 | Case series | NS (postmortem study), NA, NS | Histological | 3 | 0 | Selected† | NA |
| Beaussartw29 | Case series before-after | NS, 1 bout, 1 | EEG, neurological | 123 | 0 | Invitation | Before and after (that is, act as own controls) |
| Szymusikw30 | Case series | Long career, NA, >100 | EEG, neurological | 60 | 0 | Invitation | NA |
| Moriyasuw31 | Case-control | NS, 1 bout, NS | EEG | 10 | 300 | NS | Non-boxing head injury patients |
| Nesarajahw32 | Case-control | Mixed, NA, NS | EEG | 50 | 75 | Invitation | NS |
| Beaussartw33 | Case series before-after | Club, 1 bout, 1 | EEG | 52 | 0 | NS | Before and after (that is, act as own controls) |
| Blonsteinw34 | Case series | Knockouts, NA, NS | EEG | 29 | NA | Selected | NA |
| Pampusw35 | Case series before-after | NS, NA, 1-4 bouts | EEG, neurological | 207 | 0 | Selected | Before and after (that is, act as own controls) |
| Blonsteinw36 | Case-control | Knockouts, 1 bout | EEG | 24 | 24 | Selected | Non-knockout boxers |
EEG=electroencephalography; MRI=magnetic resonance imaging; CT=computed tomography; SPECT=single photon emission computed tomography; Pt MOA=platelet monoamine oxidase inhibitor; NA=not applicable; NS=not stated.
*Selected on basis of referral to clinic with neurological problems.
†Selected on basis of dying in psychiatric hospital and having reportedly boxed at some time in life.