Leading causes of hospitalisation in the ACT, 2016-17 to 2020-21

Report purpose

This report summarises the leading causes of hospitalisation in the ACT in the 5-year period spanning the financial year 2016–17 to the financial year 2020–21. It also provides detail on the variation in the leading causes of hospitalisation across age and sex and by the different kinds of hospitalisation. In most instances in this report where results are reported by sex, only results for males and females are presented on account of the low numbers in the “Other” and “Not stated” sex categories.

Data sources and exclusions

For the purposes of this report, the term hospitalisation is used to refer to a hospital separation. The analysis uses records sourced from the ACT Admitted Patient Care Collection with both public and private hospital records included. The analysis excludes hospitalisations for boarders, newborns with unqualified days, posthumous organ donors and non-ACT residents. Where rates are presented, the Estimated Resident Population (ERP) for the ACT is used as the denominator.¹

It should be noted that some of the hospital records for the ACT between 2016–17 and 2020–21 were not available to be included in the analysis. For more information on the data sources used in this report, including limitations of the data sources used, see Appendix A.

Determining cause of hospitalisation

The International Statistical Classification of Diseases and Related Health Problems (ICD) was developed by the World Health Organization to establish an international standard for classifying episodes of healthcare. The 10th revision of the ICD (ICD‑10) was introduced in 1997 and the Australian modification of the ICD‑10 (ICD‑10‑AM) remains the predominant system used to classify episodes of admitted patient care in Australia.

Within the ICD‑10, codes can describe diseases, symptoms, clinical test results and external factors relating to an episode of healthcare. Each code exists within a 3-character category. These 3-character categories are used for international reporting and comparisons and are sometimes referred to as the ‘core classifications’.² Core classifications are grouped together in blocks based on a common factor. Blocks are then grouped together in chapters that specify either the affected body systems, a special disease involved or the external factors that contributed to the episode of care.

In the ACT, clinical coders can add up to 100 diagnostic ICD‑10‑AM codes to each episode of hospitalisation. However, for each hospitalisation, a single ‘principal diagnosis’ code must be assigned from the ICD‑10‑AM. The principal diagnosis is defined as the condition or treatment identified as being primarily responsible for causing the admission.³ For the purpose of this analysis, the cause of a hospitalisation is considered to be the ICD‑10‑AM core classification of the principal diagnosis.

In order to assess the major causes of hospitalisation in the ACT in the period from 2016–17 to 2020–21, the principal diagnosis for all included episodes of admitted patient care were analysed. To present and compare the predominant causes of hospitalisation, the principal diagnoses are reported both by ICD‑10‑AM core classifications and by ICD‑10 chapters.

Where causes of hospitalisations are compared in this report, ICD‑10 chapters are colour coded according to the scheme in Figure 1. Where causes of hospitalisation are compared in this report using ICD‑10‑AM core classifications, the 3-character diagnostic codes are included alongside a description of the condition identified by the diagnostic code.

Figure 1: Colour coding of ICD‑10 chapters used throughout this report

Demographic summary

There were 649,764 recorded hospitalisations of ACT residents in ACT hospitals for the period 2016–17 to 2020–21. Of these, 47.2% of hospitalisations were for males and 52.8% of hospitalisations were for females (Table 1). The median age of hospitalised persons was 57 years. A total of 2.3% of those admitted were recorded as being of either Aboriginal or Torres Strait Islander origin, while 95.4% were recorded as being non-Indigenous.

Including all records, the number of hospitalisations were highest for males at the age of 75⁠–⁠79 and highest for females at the age of 30⁠–⁠34 (Figure 2). Excluding hospitalisation in the “Pregnancy, childbirth and the puerperium” WHO ICD‑10 chapter, hospitalisations for females peaked at the age of 70⁠–⁠74.

Figure 2: Age and sex distribution of hospitalised ACT residents, 2016–17 to 2020–21

Acute hospitalisations by stay duration

A same-day separation is a hospitalisation where the person is admitted and separated on the same date, while an overnight separation occurs when the person is admitted and separated on different dates.⁴

Table 2 shows the 3-character ICD‑10‑AM core classifications identified as causing the most acute hospitalisations by the duration of the hospital stay. While the leading reasons for same-day separations were ‘Care involving dialysis’, ‘Other cataract’, and ‘Other medical care’, the leading reasons for overnight separations were ‘Single spontaneous delivery’, ‘Single delivery by caesarean section’, and ‘Care involving dialysis’.

Acute hospitalisations by urgency

Most hospitalisations can be categorised as either emergency admissions, unplanned admissions that arise as a result of an emergency, or elective admissions, where there is flexibility regarding the time of the admission and the admission can be planned in advance.

Table 3 gives the top reasons for acute hospitalisations by admission urgency category. While the leading reasons for emergency admissions were ‘Care involving dialysis’, ‘Pain in throat & chest’, and ‘Abdominal & pelvic pain’, the leading reasons for elective admissions were ‘Care involving dialysis’, ‘Other cataract’, and ‘Other medical care’.

Hospitalisations for dialysis

Dialysis is a procedure for removing waste products from the blood in cases where a person’s kidneys are no longer able to adequately perform this function. Dialysis is the leading cause of hospitalisation in Australia and accounted for almost 15% of hospitalisations nationwide in the 2020‑21 financial year.⁵ As most people who require dialysis have 3 dialysis appointments per week,⁶ many of those with kidney failure are admitted to hospital over 150 times per year.

In 2016–17 to 2020–21, there were 147,468 hospitalisations of ACT residents in the ACT where a condition in the ‘Other factors influencing health status’ ICD chapter was listed as the principal diagnosis. Of these hospitalisations, 75.7% were for care involving dialysis. Hospitalisations where care involving dialysis was given as the principal diagnosis accounted for 17.2% of all hospitalisations of ACT residents in 2016–17 to 2020–21.

Males accounted for 62.1% of hospitalisations for dialysis while females accounted for 37.9% (Table 4). Hospitalisations for dialysis primarily occurred among older people, with the median age of hospitalisation for dialysis being 69 years.

Figure 3: Age distribution of ACT residents hospitalised for dialysis, 2016–17 to 2020–21

All analysis from this point will exclude records where ‘Care involving dialysis’ is listed as the principal diagnosis.

Leading conditions causing hospitalisation

ICD‑10‑AM chapters

Of the non-dialysis hospitalisations of ACT residents in the ACT between 2016–17 and 2020–21, an ICD‑10‑AM code in the “Musculoskeletal system diseases” ICD‑10 chapter⁷ was entered as the principal diagnosis in 11.8% of cases, more often than for any other ICD‑10 chapter (See Table 5).

Conditions from the ‘Injury & poisoning’, ‘Digestive system diseases’, and ‘Symptoms, signs & abnormal findings’ chapters were also major causes of hospitalisation, accounting for 11.3%, 10.6%, and 9.9% of hospitalisations respectively.

Table 5: Leading principal diagnosis of hospitalisations among ACT residents (ICD‑10 chapter), 2016–17 to 2020–21

ICD‑10 chapter	Hospitalisation	% Totala	% Femaleb	Age Spreadc
Musculoskeletal system diseases	63,681
Injury & poisoning	61,029
Digestive system diseases	56,926
Symptoms, signs & abnormal findings	53,197
Pregnancy/childbirth	37,061
Other factors influencing health status	35,849
Circulatory system diseases	34,790
Genitourinary system diseases	32,394
Respiratory system diseases	30,513
Neoplasms	26,821
Mental & behavioural disorders	19,555
Nervous system diseases	19,171
Diseases of the eye	14,703
Infectious & parasitic diseases	11,618
Skin diseases	9,820
Endocrine/metabolic diseases	9,195
Blood diseases	8,822
Perinatal period conditions	5,525
Diseases of the ear & mastoid	4,943
Congenital malformations	2,451
Excludes hospitalisations where the principal diagnosis was dialysis.
a Percentage of all hospitalisations with principal diagnosis code in ICD‑10 chapter.
b Percentage of hospitalisations with principal diagnosis code in ICD‑10 chapter where the sex of the admitted person was female.
c Age-specific rates of hospitalisation with principal diagnosis code in ICD‑10 chapter by age. Ages are grouped in 5‑year age groups from 0‑84, with an additional age group for people 85 or older. Age groups are sorted from youngest to oldest, left to right.

ICD‑10‑AM core classifications

Performing the above analysis using ICD‑10‑AM core classifications rather than ICD‑10‑AM chapters, provides more detail on the most common causes of hospitalisation in the ACT. Table 6 shows the 30 ICD‑10‑AM codes that were given as a primary diagnosis most often in the period 2016–17 to 2020–21. Collectively, these conditions constitute 34.6% of all hospitalisations of ACT residents in the ACT between 2016–17 and 2020–21.

While more males than females were hospitalised for ‘Chronic ischaemic heart disease’, ‘Fracture at wrist & hand level’, ‘Open wound of wrist & hand’, ‘Other malignant neoplasms of skin’, and ‘Cerebral infarction’, more females than males were hospitalised for ‘Single delivery by forceps & vacuum extractor’, ‘Single delivery by caesarean section’, ‘Single spontaneous delivery’, ‘Other rheumatoid arthritis’, and ‘Abdominal & pelvic pain’.

Table 6: Leading principal diagnosis of hospitalisations among ACT residents (ICD‑10‑AM core classification), 2016–17 to 2020–21

ICD‑10‑AM core classification	Hospitalisations	% Totala	% Femaleb	Age Spreadc
M17) Gonarthrosis [arthrosis of knee]	18,036
M16) Coxarthrosis [arthrosis of hip]	15,107
R07) Pain in throat & chest	12,805
O80) Single spontaneous delivery	11,891
H26) Other cataract	11,011
Z51) Other medical care	10,785
R10) Abdominal & pelvic pain	9,375
O82) Single delivery by caesarean section	8,458
K50) Crohn's disease [regional enteritis]	6,626
J18) Pneumonia, organism unspecified	5,151
M54) Dorsalgia	4,451
N39) Other disorders of urinary system	4,385
K80) Cholelithiasis	4,373
L03) Cellulitis	4,083
M06) Other rheumatoid arthritis	3,962
S52) Fracture of forearm	3,949
I48) Atrial fibrillation & flutter	3,924
I50) Heart failure	3,792
Z45) Adjustment & management of drug delivery or implanted device	3,779
S61) Open wound of wrist & hand	3,778
J44) Other chronic obstructive pulmonary disease	3,762
O81) Single delivery by forceps & vacuum extractor	3,734
I25) Chronic ischaemic heart disease	3,699
S72) Fracture of femur	3,688
C44) Other malignant neoplasms of skin	3,680
S62) Fracture at wrist & hand level	3,675
I63) Cerebral infarction	3,669
A09) Other gastroenteritis & colitis of infectious & unspecified origin	3,626
J35) Chronic diseases of tonsils & adenoids	3,613
F10) Mental & behavioural disorders due to use of alcohol	3,315
Excludes hospitalisations where the principal diagnosis was dialysis.
a Percentage of all hospitalisations with 3-character ICD‑10‑AM grouping as the principal diagnosis code.
b Percentage of hospitalisations with a given 3-character ICD‑10‑AM grouping where the sex of the admitted person was female.
c Age-specific rates of hospitalisation with principal diagnosis code by age. Ages are grouped in 5‑year age groups from 0‑84, with an additional age group for people 85 or older. Age groups are sorted from youngest to oldest, left to right.

Causes of hospitalisation by age and sex

ICD‑10 chapters

As shown in Table 5 and Table 6 above, there was considerable variation in the rates of hospitalisation for different conditions between different sexes and age groups. Figure 4 shows how the 5 ICD‑10‑AM chapters responsible for the most hospitalisation differ by both age group and sex. Conditions in the ‘Perinatal period conditions’, ‘Respiratory system diseases’, and ‘Symptoms, signs & abnormal findings’ chapters contributed most to hospitalisations for both males and females in the under 5 years age group and conditions in the ‘Injury & poisoning’, ‘Digestive system diseases’, and ‘Respiratory system diseases’ chapters contributed the most to hospitalisations of both males and females in the 5 to 14 years age group. However, in older age groups, the chapters responsible for the most hospitalisations differed for males and females.

Figure 4: Leading 5 principal diagnoses of hospitalisations among ACT residents by age group and sex (ICD‑10 chapter), 2016–17 to 2020–21

ICD‑10‑AM 3-character groupings

Figure 5 shows how the 5 ICD‑10‑AM 3-character groupings responsible for the most hospitalisation differ by both age group and sex. Among the top conditions, 4 were common to both sexes for the Under 5 and 65+ age groups, 3 were common to both sexes for the 5⁠–⁠14 and 45⁠–⁠64 age groups, 2 were common to both sexes for the 15⁠–⁠24 age group, and 1 was common to both sexes for the 25⁠–⁠44 age group.

Figure 5: Leading 5 principal diagnoses of hospitalisations among ACT residents by age group and sex (ICD‑10‑AM core classification), 2016–17 to 2020–21