Statement of Principles concerning ankylosing spondylitis (Reasonable Hypothesis) (No. 39 of 2021)

This instrument is a legislative determination made under subsection 196B(2) of the Veterans’ Entitlements Act 1986 (VEA) by the Repatriation Medical Authority. It sets out the factors that must exist to raise a reasonable hypothesis connecting ankylosing spondylitis, or death from that condition, with the relevant service of a veteran, peacekeeper, or member of the Forces under the VEA, or a member under the Military Rehabilitation and Compensation Act 2004 (MRCA). The instrument operates as an evidentiary standard for claims to which section 120A of the VEA or section 338 of the MRCA applies. Mechanically, it replaces the need for case-by-case medical evidence of causal connection by providing a codified checklist of minimum factors. At least one of five listed factors must exist before a reasonable hypothesis can be said to be raised: periodontitis for at least three months before clinical onset or clinical worsening; current smoking of at least one pack-year before clinical worsening; obesity for at least five years within the ten years before clinical worsening; or inability to obtain appropriate clinical management for the condition. The instrument does not itself grant or deny compensation; it merely establishes the threshold for a reasonable hypothesis, which is a lower standard than the balance of probabilities. The effect is to centralise medical-scientific assessment of causation into a single, generally applicable standard, reducing adjudicative discretion but also imposing rigid categories that may not capture every plausible causal pathway. The instrument applies only to claims involving relevant service as defined in Schedule 1, which includes operational, peacekeeping, hazardous, and British nuclear test defence service under the VEA, as well as warlike and non-warlike service under the MRCA. The definition of ankylosing spondylitis excludes psoriatic arthritis, reactive arthritis, and fibromyalgia, narrowing the scope of conditions to which the instrument applies. The instrument was amended once, on 19 September 2022, to revise the definition of “one pack-year” and the corresponding note in section 9(3).

The central concept is the “reasonable hypothesis” standard. This is a lower evidentiary threshold than proof on the balance of probabilities. It requires that there be a hypothesis that is reasonable, meaning it is not fanciful, impossible, or obviously untenable, and that is grounded in sound medical-scientific evidence. The Repatriation Medical Authority states in section 8 that it is of the view that there is sound medical-scientific evidence indicating that ankylosing spondylitis and death from it can be related to relevant service. That view is the basis for the instrument’s content.

Ankylosing spondylitis is defined in section 7(2) as “a chronic, progressive, systemic inflammatory disease principally involving the sacroiliac joints and the axial skeleton”. The note to that subsection clarifies that typical features include HLA B27 antigen, onset before age 45, elevated C-reactive protein, peripheral arthritis, heel enthesitis, uveitis, or a family history of spondyloarthritis. The definition explicitly excludes psoriatic arthritis, reactive arthritis, and fibromyalgia. The ICD-10-AM code M45 is assigned for administrative purposes, but the substantive definition in subsection (2) governs application. Death from ankylosing spondylitis includes death from a terminal event (pneumonia, respiratory failure, cardiac arrest, circulatory failure, or cessation of brain function) that was contributed to by the person’s ankylosing spondylitis.

The factors in section 9 are the minimum elements required. Each factor has its own definition or condition. “Periodontitis” is not defined in the instrument, leaving its meaning to ordinary medical usage. “One pack-year” is defined as the amount of tobacco consumed in smoking 20 cigarettes per day for one year, or an equivalent amount of 7300 grams of smoking tobacco by weight. The formula for calculation is specified. “Being obese” is defined as having a BMI of 30 or greater, with BMI defined as weight in kilograms divided by the square of height in metres. The factor for obesity requires the person to have had that BMI for at least five years within the ten years before clinical worsening, not merely at the time of worsening. “Inability to obtain appropriate clinical management” includes inability to undertake prescribed ankylosing spondylitis exercises, which are defined as regular stretching and range of motion exercises together with either aerobic or group exercises.

The instrument distinguishes between clinical onset (factors (1)) and clinical worsening (factors (2), (3), (4), (5)). For worsening, the section 10(2) provides that the factors apply only to material contribution to, or aggravation of, ankylosing spondylitis where the person’s condition was suffered or contracted before or during (but did not arise out of) the person’s relevant service. This means that for a worsening claim, the service must not have caused the original condition but must have contributed to its aggravation.

The instrument directly affects any person who has rendered relevant service as defined in Schedule 1 and who claims to suffer from ankylosing spondylitis, or who claims that a death from ankylosing spondylitis is service-related. Relevant service includes operational, peacekeeping, hazardous, and British nuclear test defence service under the VEA; and warlike and non-warlike service under the MRCA. This covers current and former members of the Australian Defence Force, peacekeepers, and certain civilians who served in British nuclear tests. It also affects veterans’ dependants making death claims.

Indirectly, the instrument affects the decision-makers within the Department of Veterans’ Affairs and the Military Rehabilitation and Compensation Commission who must apply it to claims. They are bound by its terms and cannot consider factors outside the list unless the claim involves a new factor not yet covered by any SOP. The instrument also affects medical practitioners who must provide evidence that a factor exists, such as confirming a diagnosis of periodontitis, calculating pack-years, documenting BMI over time, or certifying that prescribed exercises were unavailable. The Repatriation Medical Authority is the body that determined the instrument and must keep the evidence base under review, though the instrument does not impose a review cycle. The instrument does not affect persons with ankylosing spondylitis who are not covered by the VEA or MRCA, such as civilian workers covered by other compensation schemes or private litigants. It also does not affect persons whose ankylosing spondylitis arises from service that does not fall within the nine categories of relevant service. For those persons, the ordinary rules of evidence and causation under the VEA or MRCA apply without the benefit of this codified standard.

The instrument does not create duties or rights in the same way that a primary Act does, but it does impose obligations on decision-makers and confers evidentiary benefits on claimants. The Repatriation Medical Authority has the duty to determine Statements of Principles based on sound medical-scientific evidence. Section 8 records its view that such evidence exists, which is a precondition for the instrument’s validity.

A claimant has the right to rely on any one of the five factors in section 9 to raise a reasonable hypothesis connecting their ankylosing spondylitis with their relevant service. The factors are alternative, not cumulative: only one need exist. The claimant also has the right to rely on the cross-reference provision in section 11, which provides that if a factor refers to an injury or disease covered by another Statement of Principles, then the factors in that other SOP apply. For example, if periodontitis is a factor, the claimant may need to meet the factors in the periodontitis SOP to establish that they have periodontitis related to service.

The decision-maker has a duty to apply the instrument as a mandatory standard when assessing whether a reasonable hypothesis exists. They cannot substitute their own judgment about causation if none of the factors are met, unless the claim involves a novel factor not contemplated by any SOP. The instrument does not give the decision-maker discretion to waive or modify the factors.

For worsening claims, section 10(2) imposes a limitation: factors (2) to (5) (periodontitis for worsening, smoking, obesity, inability to obtain clinical management) apply only where the ankylosing spondylitis was suffered or contracted before or during relevant service but did not arise out of that service. This means that if the condition arose out of service, the worsening factors are not needed; but if it pre-existed or was contracted during service without causal connection, the worsening factors become relevant.

Claimants have no right to compensation merely because a factor exists; the instrument only addresses the reasonable hypothesis standard. The actual entitlement to a pension or other benefit depends on other provisions of the VEA or MRCA. The instrument also does not create any duty on third parties, such as employers or medical providers, to provide treatment or data.

This instrument itself contains no penalty provisions. Enforcement occurs through the claims process under the VEA and MRCA. If a claimant falsely asserts that a factor exists, they may face penalties under section 136 of the VEA (offences relating to false statements) or under the Criminal Code for fraud. Similarly, a medical practitioner who knowingly provides false evidence of periodontitis, smoking history, or BMI could be liable for perjury or giving false information to obtain a benefit. The instrument does not create civil penalties for non-compliance by the decision-maker; any failure to apply the instrument correctly can be challenged in the Administrative Appeals Tribunal or the Federal Court through judicial review.

The practical enforcement mechanism is that claims are assessed and, if the factor is not established, the claim is refused. The burden of proof rests on the claimant to raise the reasonable hypothesis. The decision-maker must be satisfied that at least one factor exists and that it is related to service. If the decision-maker incorrectly rejects a claim, the remedy is internal review or external merits review. If the decision-maker incorrectly accepts a claim despite no factor being present, the overpayment may be recovered under the VEA or MRCA provisions. The instrument does not provide for any specific auditing or compliance regime; it is enforced through the ordinary administrative law framework.

The amendment to the definition of “one pack-year” in 2022 may affect how smoking histories are calculated, and any misapplication of the old definition could lead to incorrect decisions. The instrument’s definitions are legally binding; if a decision-maker uses a different calculation method, that could be an error of law subject to appeal.

The instrument is made under subsection 196B(2) of the VEA and applies to claims under section 120A of the VEA and section 338 of the MRCA. Those provisions require the decision-maker to apply the relevant Statement of Principles when determining whether a reasonable hypothesis exists. The instrument therefore modifies the standard of proof in those claims by providing a codified list of acceptable factors.

The instrument also interacts with other Statements of Principles. Section 11 provides that if a factor refers to an injury or disease covered by another Statement of Principles (e.g., periodontitis may be covered by a separate SOP), then the factors in that other SOP apply in accordance with its terms as in force from time to time. This creates a chain of instruments: a claimant for ankylosing spondylitis may need to rely on the periodontitis SOP to establish that factor. Those cross-referenced SOPs are also made under the same provision and have similar structure.

The instrument defines terms that are also used in the VEA and MRCA. For example, “relevant service” is defined in Schedule 1 using the categories from those Acts, but the instrument does not alter the meaning of those categories; it merely adopts them. “Terminal event” is defined for the purpose of death claims, which interacts with the VEA’s provisions on dependants’ claims.

The instrument does not interact with state workers’ compensation laws, the Safety, Rehabilitation and Compensation Act 1988, or common law claims. It is specific to the VEA and MRCA schemes. However, the definition of ankylosing spondylitis excludes conditions such as psoriatic arthritis and reactive arthritis, which may be covered by other SOPs. A person with those conditions must rely on separate instruments.

The note to section 7(2) provides clinical guidance but is not legally binding; it is explanatory only. The ICD-10-AM code reference is for administrative convenience, but the substantive definition in subsection (2) governs. Any conflict between the ICD code and the definition would be resolved in favour of the definition.

The instrument was originally made on 29 March 2021, registered as F2021L00364, and commenced on 27 April 2021. It was amended by the Veterans’ Entitlements (Statements of Principles,definition of “one pack-year”) Amendment Determination 2022 (No. 94 of 2022), registered on 26 August 2022 and commencing on 19 September 2022. The amendment substituted the definition of “one pack-year” in Schedule 1 and revised the note in subsection 9(3). The original definition is not reproduced in the compilation, but the amendment history at endnote 4 indicates that both the note and the definition were replaced. The amendment was made to standardise the definition across all Statements of Principles, as indicated by the title, which refers to the definition of “one pack-year” generally. No other provisions were amended. Sections 2 and 4 were repealed by operation of the Legislation Act 2003 (sections 48D and 48C respectively) as part of the standard drafting process for legislative instruments that omit formal provisions after registration. These repeals are administrative and do not affect the substance. There are no uncommenced amendments affecting this compilation. The instrument is now in its first compilation, dated 19 September 2022. The amendment history is straightforward and does not indicate any controversy or remedial changes to the factors themselves; only the method of calculating smoking exposure was clarified. This suggests that the original definition may have been ambiguous or inconsistent with other SOPs, and the 2022 amendment resolved that issue.

The instrument as a legislative instrument does not record any litigation history. The source text provides no case citations, tribunal decisions, or court judgments. However, Statements of Principles generally are frequently litigated in the Administrative Appeals Tribunal and the Federal Court, particularly on questions of whether the Repatriation Medical Authority had sufficient evidence to include a factor, or whether a particular factor is properly interpreted. Given that no litigation is mentioned, it is likely that this specific instrument has not been the subject of a reported decision, or if it has, the instrument itself does not note that. The absence of litigation history does not mean the instrument is uncontroversial; it may simply reflect that disputes are resolved at the administrative level or that the instrument is relatively new. Practitioners should be aware that the interpretation of “periodontitis” (undefined) and the calculation of the five-year obesity period could give rise to disputes. The definition of “one pack-year” was amended, possibly to address a litigation issue, but that is speculation not grounded in the source. The instrument should be read in conjunction with any AAT or court decisions that interpret the same or similar factors in other SOPs. The cross-reference to other SOPs in section 11 may also import litigation history from those instruments. Claimants and decision-makers should not assume that the instrument’s factors are immune to challenge; they can be contested on the grounds that the medical-scientific evidence does not support the factor, but the instrument is binding unless set aside by a court on judicial review.

Several traps exist for the unwary. First, periodontitis is not defined in the instrument. The term may be interpreted differently by dentists and rheumatologists, and the claimed duration of “at least three months” before onset or worsening requires precise dating of both the periodontitis diagnosis and the clinical onset or worsening of ankylosing spondylitis. If the periodontitis is not documented with a date, the factor may fail.

Second, the smoking factor applies only to “current smokers”. Former smokers who have quit before clinical worsening cannot rely on this factor, even if they have a substantial pack-year history. The factor also applies only to clinical worsening, not onset. A claimant whose ankylosing spondylitis first appeared while they were a heavy smoker cannot use smoking to raise a reasonable hypothesis for onset; only for worsening. This is a significant limitation. Also, the smoking factor is defined by the amount smoked (one pack-year), not by duration alone. A person who smoked 10 cigarettes a day for two years has only one pack-year, but if they smoked 5 a day for two years, they have only 0.5 pack-years, which is insufficient.

Third, the obesity factor requires a BMI of 30 or greater for at least five years within the ten years before clinical worsening. A claimant who was obese for only four years, or who became obese only after clinical worsening, cannot meet the factor. The BMI must be documented over time; retrospective self-reporting may be challenged.

Fourth, the “inability to obtain appropriate clinical management” factor includes inability to undertake prescribed ankylosing spondylitis exercises. The definition of those exercises is specific: regular stretching and range of motion exercises, together with either aerobic exercises or group exercises. If the prescribed exercises differ (e.g., only stretching), the factor may not be satisfied. Also, the inability must be due to circumstances of service, such as being deployed to a location where no physiotherapy is available. A simple dislike of exercise is not sufficient.

Fifth, the relationship to service requirement in section 10(2) restricts factors (2) to (5) to aggravation cases where the condition did not arise out of service. If the ankylosing spondylitis first arose during service and is causally connected, the worsening factors are not needed; but if the condition is accepted as arising out of service, the claim may succeed without them. Conversely, if the condition pre-existed service and is worsened, the worsening factors apply, but only if the original condition was not caused by service. This nuance is often misunderstood.

For a claimant, compliance means gathering evidence to support at least one of the five factors, and then establishing the relationship of that factor to relevant service. For periodontitis (factor (1) or (2)), obtain dental records or a specialist report confirming the diagnosis and the date of onset, and show that periodontitis was present for at least three months before the clinical onset or worsening of ankylosing spondylitis. The clinical onset or worsening must itself be documented, typically by a rheumatologist’s report with dates of first symptoms or flare-ups.

For smoking (factor (3)), the claimant must be a current smoker at the time of clinical worsening. Obtain a smoking history with a calculation of pack-years: number of cigarettes per day divided by 20, multiplied by the number of years smoked, using the formula in the note to the definition. For equivalent tobacco products (pipe, cigars), use 7300 grams per pack-year. The smoking must have occurred before the clinical worsening, and the worsening must be documented. If the claimant has quit smoking before worsening, this factor cannot be used.

For obesity (factor (4)), obtain weight and height records showing a BMI of 30 or greater for a cumulative total of at least five years within the ten-year period immediately before clinical worsening. Medical records, service medical files, or repeated measurements are ideal. Self-reported weight is less reliable. The ten-year window is rolling; the claimant does not need to be obese at the exact moment of worsening, but the five years must fall within the ten years prior.

For inability to obtain appropriate clinical management (factor (5)), produce evidence that the claimant was prescribed or recommended ankylosing spondylitis exercises (as defined), and that due to service circumstances (e.g., remote posting, lack of facilities, operational requirements) they could not undertake those exercises. A letter from a physiotherapist or medical officer documenting the prescription and the unavailability of facilities is useful. The inability must be related to service; a civilian lack of motivation does not count.

For death claims, the claimant must show that ankylosing spondylitis contributed to a terminal event, and that the terminal event was the proximate or ultimate cause of death. A medical report attributing death to, say, respiratory failure secondary to ankylosing spondylitis, with the condition having been service-related, is required.

The decision-maker must apply the instrument strictly. They should verify that the claimed factor meets the definitional requirements, especially the temporal conditions. For obesity, they must confirm that the five years of obesity fell within the ten years before worsening, not after. For smoking, they must ensure the smoking occurred before worsening and that the claimant was a current smoker at the time of worsening. For the relationship to service, they must apply section 10(1): the factor must be related to the person’s relevant service. This may involve examining service records to see if the factor (e.g., periodontitis) was diagnosed during service, or if smoking was a consequence of service-related stress. The decision-maker should also check section 11 to see if any factor refers to an injury or disease covered by another SOP, and if so, apply that SOP. They must use the definition of “one pack-year” as amended in 2022 for claims decided after 19 September 2022. For earlier claims, the old definition may apply, but the compilation does not reveal what that definition was, so the original instrument must be consulted.