A total of 1,171,713 presentations to Perth EDs were recorded between the 1 July 2000 and 31 December 2004. Of these, 22,655 (1.9%) were coded with "back pain" as the primary complaint. Table 1 summarises the results for all back pain presentations, the "muscular group" and the "non-muscular" group.
The most common age group was between 35 and 44 (Figure 1). Females presented in significantly larger numbers in the older age groups (75 years and over) and also in adolescence (15-24) (p < 0.005) (Figure 1).
Patients presented most often on Sundays with a gradual decrease in presentations until Friday before increasing on Saturday. A slightly disproportionately higher number of presentations occurred on weekends, with 30.2% of back pain presentations occurring on Saturday and Sunday.
Presentations were most common between 0800 and 1400, accounting for 35.8% of total presentations, but large numbers of presentations continued until midnight. Relatively few patients (13.8%) presented between midnight and 0600 (Figure 2).
Overall, a quarter of patients (5,747, 25.4%) were admitted, with females admitted more often than males (27.2% vs. 23.4%, p < 0.005).
The majority of patients (88.9%) presented only once. However 2,125 patients had multiple presentations, with one individual presenting 104 times with back pain during the data collection period. The mean number of presentations was 1.2 attendances, with 97% of patients presenting only once or twice.
When presentations were analysed by cause, 43.8% (9,926) were diagnosed as a muscular problem or non-specific back pain ("muscular" group). The remaining 56.2% (12,729) were diagnosed as due to other medical and surgical causes ("non-muscular" group). Of this group, 1,066 (8.4%) did not wait for treatment. "Did not wait" or similar applied to 610 of these at time of discharge with the remaining 456 having a diagnosis made, but not waiting for subsequent treatment. Males were significantly more likely to not wait for treatment (p < 0.005).
Muscular causes of pain were relatively rare in children under the age of 15 (2.0%).
Presentations for muscular pain occurred predominantly during the hours 0800-1400 (39.4% of presentations), with nearly 50% occurring in the 8 h between 0800 and 1600.
Only 17.1% of people in the "muscular" group required admission, but those admitted remained in hospital an average of 6.4 days (SD 10.7 days). One person was hospitalised for 163 days.
"Non-muscular" group results
In the "other" group, females represented 53% of the 12,729 presentations, significantly more than males (p < 0.005). The most common age groups remained the 25-34 and 35-44 groups, but the distribution of ages of those presenting was more spread, with much higher numbers in the 0-14 year age groups and 75+ age groups. Of 107 children below the age of 5 years who presented with back pain, 99 (92.5%) had a diagnosis other than muscular, and of those between the ages of 5 and 15, 69.1% (431 of 623 patients) were also in this group. Similarly, of those patients over 75 years of age presenting with back pain, 60.4% (1,756 of 2,904) had causes that were found to be non-muscular (Figure 3).
The admission rate for "non-muscular" category was 31.8%, significantly more than that for muscular causes (p < 0.005). However, those who were admitted had a mean length of stay of 5.8 days (SD 8.8 days), significantly less than those admitted for muscular causes (p < 0.005). The mean length of time spent in the ED was 5.1 h, 4.1 of these after being seen by the doctor. These times were significantly longer than for patients in the muscular group (p < 0.005).
There was significantly higher mortality at each time point (in ED, 2 days and 30 days after presentation) than for muscular back pain (p < 0.005).
The most common diagnoses made in the ED for those people in the "non-muscular" group were:
Renal colic (9.7%)
Urinary tract infection or pyelonephritis (6.4%)
No disease found (2.6%)
The most common hospital discharge diagnoses for all patients presenting with back pain who required admission were:
Back pain (18.8%)
Renal colic (13.7%)
Lumbar sprain (11.1%)
Pyelonephritis or urinary tract infection (6.6%)
Vertebral crush fracture (3.6%)
Abdominal pain (2.3%)
Intervertebral disc prolapse (2.3%)
Back pain was the presenting complaint in 47 cases of angina and 24 cases of myocardial infarction. A total of 53 patients with pulmonary emboli presented with back pain, and 13 episodes of pancreatitis presented with back pain as the primary complaint.
Seventeen cases of dissecting aortic aneurysms were diagnosed in the ED in patients presenting with back pain. Eighteen ruptured abdominal aortic aneurysms (AAA) were diagnosed in the ED. There were five deaths within 48 h of presentation from these 18 patients, with 3 in the ED.