We identified 2995 young people and adults admitted to hospital with a head injury, of whom 2962 lived in Glasgow. Comparison with routine hospital data showed that we had identified more than 99% of relevant cases, but 20% of those we had identified were not contained in health service statistics.
The characteristics of the cohort agreed with previous surveys1
: 1255 (42%) were men aged 40 years or less, 575 (19%) were men and women aged 65 years or more, and most (90%) were classified as having a mild injury. The most common causes of injury were falls (43%) or assaults (34%); alcohol was often involved (61%), and a quarter reported treatment for a previous head injury. Most (83%) were discharged within 48 hours (see table B on website).
We excluded the 33 patients who lived outside Glasgow. We aimed to follow up all patients with severe (102 patients) or moderate (133) head injuries and a random sample of patients with mild (507) and unclassified (28) injuries, stratified by presenting hospital and randomly selected by using a computer generated list (table ). For logistical reasons we excluded one of the severely injured patients. We successfully followed up 549 (71%) of the 769 patients selected. The rate of follow up was similar for the categories of severity (mild 71%, moderate 73%, severe 72%), and the characteristics of those successfully followed up were closely representative of the randomly selected group (table ), apart from those who were not traced having a shorter hospital stay (80% v 71% for a stay of ≤2 days) and being given a return appointment less often (9% v 22%).
Severity of head injury in young people and adults admitted to hospital over one year in Glasgow, in the cohort selected for follow up, and in those successfully followed up. Values are numbers (percentages) unless stated otherwise
Early characteristics of patients selected for follow up and those successfully followed up. Values are numbers (percentages) unless stated otherwise
Outcome at one year
Increased severity of injury on admission (table ) was associated with an increased rate of death or vegetative state (χ2=42.7, 1df, P<0.001) and a decreased rate of good recovery (20.6, df=1, P<0.001). In contrast, the initial severity of injury was not related to late disability (0.00, df=1, P=0.95), which occurred in almost half of each group: mild (47%, 95% confidence interval 42% to 52%), moderate (45%, 35% to 56%), and severe injury (48%, 36% to 60%). Most survivors of severe head injury (78%) were disabled; disability was also common and occurred at a similar rate in survivors of mild (51%) and moderate injuries (54%).
Outcome related to initial severity of head injury one year later. Values are numbers (percentages) unless stated otherwise
Specific problems were reported most often after severe injury, but were also common in survivors of moderate or mild injury (table ) (see table C on website). Increased dependency was reported in 15 of 33 survivors of severe injury (45%), 21 of 70 (30%) survivors of moderate injury, and 88 of 310 (28%) survivors of mild injury. Employment status before injury was known for 407 patients (39 severe, 77 moderate, 291 mild). The number of patients who were in paid employment, were housewives, or were in further education decreased from 173 (42%) before injury (18 severe, 30 moderate, 125 mild) to 116 (28%) after injury (5 severe, 25 moderate, 79 mild). The number of patients unfit for work increased from 64 (16%; 5 severe, 8 moderate, 52 mild) to 130 (32%; 22 severe, 17 moderate, 91 mild) including 43 (33%; 12 severe, 3 moderate, 29 mild) of those previously employed.
Distribution of outcome and problems reported for survivors of mild, moderate, and severe head injuries. Values are numbers (percentages) unless stated otherwise
Of the disabled survivors, less than half (114, 47%) were seen in hospital after discharge, and only 71 (28%) were reported as having received input from rehabilitation services. Despite the predominance of “mental” sequelae, the most commonly provided service was physiotherapy. Only 37 patients (15%) had contact with social work services. The most common contact reported for disabled survivors was with their general practitioner (91%), but only 117 (54%) of such contacts were related to the head injury
Incidence of disability
Of the initial cohort, 2668 had mild injuries, 133 moderate injuries, and 102 severe injuries; in 59 severity was unknown. On the basis of the proportion of patients assessed at one year to be severely or moderately disabled (47%, 45%, 48% and 47% respectively in the four categories), we estimate that 1397 survived with disability. Of these, 1260 (90%) had had mild injuries. In the Glasgow population of 909
498 (statistics for 1995-6 from the general register office, Scotland) this corresponds to a rate of 154 per 100
000 population (95% confidence interval about 138 to 169, taking account only of the statistical variability in the rates of survivors with disability). Even assuming that all patients not assessed at one year had made a good recovery, a rate of more than 100 per 100
000 population can still be projected.
Predictors of death or disability in mildly injured patients
A univariate analysis restricted to patients who were mildly injured identified age, sex, cause of injury, pre-existing physical limitations, and a documented history of brain illness as significant predictors of death or disability at one year (table ). A multivariate logistic regression analysis identified age of more than 40 years (odds ratio 1.80, 1.11 to 2.91), pre-existing physical limitations (2.24, 1.30 to 3.86), and a history of brain illness (2.07, 1.33 to 3.21) as independent predictors of a poor outcome. Nevertheless, 107 of the 362 mildly injured patients had none of these predisposing risk factors, yet 37 (35%) still failed to achieve a good recovery. In these analyses patients with missing data on medical history were assumed not to have a history of the relevant condition, but this applied to only 10 of the 107 patients and should not have introduced substantial bias.
Predictors of death and disability in 362 mildly injured patients. Values are numbers (percentages)