This is the second overview report by the National Injury Surveillance Unit, on national hospital separations due to injury and poisoning, for the data year 1999-00.

The term 'separations' refers to the number of cases separating from hospital, and is not equivalent to newly incident cases. There may be more than one separation per incident case. This is the first report in the series to be based entirely on data coded according to ICD-10-AM (first edition).

Main findings

In 1999-00, 413,647 hospital separations due to injury and poisoning were reported. This accounted for 7% of total hospital separations for that time period.

Females accounted for 42.4% of injury separations (n=175,256), the male to female rate ratio (based on age-standardised separation rates) was 1.4:1.

Age-specific hospitalisation rates increased from birth to the 20-24 year age group for both sexes. Thereafter, the rate was relatively constant for females, increasing at the 50-54 year age group. Male rates were higher than female rates from birth to the 70-74 year age group. Female rates overtook male rates at that point, with both sexes reaching maximum rates in the 85+ year age group.

Falls were the most commonly reported external cause of injury, accounting for 29% of all injury separations, followed by Other unintentional (26.7%) and Complications of medical and surgical care (16.5%).

Falls were most common for both sexes at ages 0-14 years (38% of all injury separations at these ages) and at 65 years and older (55% of injury separations). The rate of separations due to Falls was 2,143 per 100,000 population at ages 65 and older, and 7,894 per 100,000 at ages 85+ years.

Separations attributed to Complications of medical and surgical care increased with age, from 9% in the 20-34 year age group to 27% in those aged 65 years and above.

Intentional self-harm accounted for 5% of separations, with rates per 100,000 population highest in the female 15-19 year (288.3), and male 25-29 year (191.5) age groups.

Overall, male rates exceeded female rates for all external causes except for Poisoning, pharmaceutical (X40-X44), Falls (W00-W19) and Intentional, self- inflicted (X60-X84 and Y87.0).

Of the cases for which a Place of Occurrence code was required (i.e. cases with an external cause code in the range W00-Y34, excluding Y06 and Y07), Home was the place specified most commonly, especially for females, children and older persons. Residential institutions were the next most commonly specified place for older persons, but were uncommon for younger groups. The second most commonly specified place for children and younger adults (especially males), was Sports and athletics areas.

Of the 121,616 injury cases for which a Place of occurrence code was not required, 56% (n=68,193) were attributed to Complications of medical and surgical care, and 42% (n=51,486) to Transportation.

Of the 344,704 injury separations during 1999-00 for which an Activity code was required, about half had an uninformative value (i.e. Unspecified Place). 7.2% of injury separations (9.7% of male cases) were recorded as occurring during sport, and 7.0% of injury separations (10.5% of male cases) occurred while working for income (i.e. occupational injuries).

Shoulders and upper limbs was the most commonly injured body region among hospitalised injuries for persons, comprising 24.9% (n=103,187) of total cases. Injuries to these areas of the body accounted for a larger proportion of male than of female separations (ratio of nearly 2:1). Wrist and hand injury rates were much higher for males than females, except in early childhood and old age. Much of the highest rates were seen for males from 15 years to mid-adult ages. Rates for females did not vary very much with age.

Hip and lower limb injuries accounted for 23.3% of female cases and 18.2% of male cases. Rates are high for older age groups.

Head injuries were the third most frequent injury diagnosis overall (n=62,237). The number of male head injury separations (n= 42,375) was about twice the female count (n=19,862). Head injury rates for males were high in the 0-4 year age group (638 separations per 100,000 population), and the 15-19 year age group (877 separations per 100,000 population). Both male and female head injury rates were highest in the 85+ year age group (1,038 and 1,060 respectively). The all ages rate for males was over twice as high as the rate for females.

The average length of stay (ALOS) in 1999-00 for injury and poisoning was 4 days (1,737,236 bed days over 413,647 separations). Discharge occurred on the day of admission for 29% (n=120,156) of these separations. Removing same day cases (except deaths and transfers to acute care hospitals), the total number of bed days was 1,617,080 over 293,491 separations, resulting in an average of 5.5 bed days per separation. About 33% of injury separations were after a stay of three days or more (n=136,081).

Complications of surgical & medical care, not elsewhere classified was the Principal Diagnosis accounting for the largest number of bed days (just over 400,000).

Injuries to the hip and thigh ranked second highest in terms of total bed days (n=321,864). Females were over represented in this injury category at a M:F ratio of just over 1:2. Hip and thigh injury hospitalisations had the longest ALOS per separation among the groups considered (n=11 days), the next longest being for Injuries to the abdomen, lower back, lumbar spine and pelvis (n=7 days).

Nearly 84% of all injury cases were discharged to their usual residence. The proportion was highest for children (93% at ages 0-14 years) and lower for older people (68% at 65+ years).