Prevalence and predictors of polypharmacy and psychotropic use among Australian Defence Force veterans transitioning from military to civilian life

Abstract

Background

Polypharmacy is a growing concern among veterans due to high rates of multi-morbidity and its complex pharmacologic management. This study examined the prevalence and predictors of polypharmacy among Australian Defence Force (ADF) veterans transitioning from military to civilian life.

Methods

A retrospective cohort analysis was conducted using electronic medical records from 1210 ADF veterans attending a medical service. General polypharmacy was defined as ≥5 medications, and psychotropic and other N-class polypharmacy as ≥2 medications within those classes. Multivariable logistic regression identified demographic and clinical predictors.

Results

General polypharmacy occurred in 19.1% of veterans, psychotropic polypharmacy in 9.8% and other N-class polypharmacy in 14.6%. Veterans with post-traumatic stress disorder (PTSD) had significantly higher rates of psychotropic (25.9% vs 4.5%) and general polypharmacy (33.7% vs 14.4%) (p < .001). Psychiatric comorbidity burden was the strongest predictor of psychotropic polypharmacy (OR 1.91), while PTSD independently doubled the odds (OR 2.07). General polypharmacy was primarily associated with medical (OR 1.51) and psychiatric comorbidities (OR 1.41).

Conclusions

Polypharmacy is common among Australian veterans transitioning from military to civilian life, particularly those with PTSD and multiple comorbidities, highlighting the need for early medication review and deprescribing strategies.

Keywords

polypharmacy psychotropic medications PTSD comorbidity pharmacoepidemiology

Military service exposes personnel to extreme physical and psychological stress, imposing a risk of chronic psychiatric and physical conditions that affect health and well-being. In 2010, 22% of the regular Australian Defence Force (ADF) had a psychiatric disorder, with approximately 6.8% diagnosed with more than one concurrent disorder.¹ The prevalence of psychiatric disorders is also concerning in ADF members who have transitioned from military to civilian life, with nearly half of an Australian cohort experiencing a psychiatric disorder in the past year.² Notably, 80% of those with PTSD had another comorbid psychiatric disorder. Similarly, transitioned ADF members have poorer physical health than those currently serving, including more physical health symptoms, service-related injuries and a greater risk of circulatory, cardiac and musculoskeletal conditions.^2,3

The presence of comorbid psychiatric and physical illnesses,⁴ sleep disturbances⁵ and chronic pain^6,7 increases the likelihood of polypharmacy (concurrent use of multiple medications) and its inherent risks. Psychotropic polypharmacy (use of ≥ two drugs that can affect cognition, thoughts and mood) is particularly concerning due to little evidence supporting the safety and effectiveness of drug combinations.^8,9

Veterans face challenges when transitioning from military to civilian life, such as loss of purpose and identity, social isolation and securing employment.¹⁰ The need for pharmaceutical management of multiple health conditions substantially increases those challenges. Psychotropic medications, in particular, may affect cognitive and psychomotor functioning, with potential impacts on daily activities, safety and overall quality of life.^11–14

A recent meta-analysis exploring the prevalence of polypharmacy in military and veteran populations reported a pooled prevalence of psychotropic polypharmacy of 36%,¹⁵ with a higher rate in those with PTSD. However, these studies were predominantly from the U.S. Data on psychotropic prescribing in Australian veterans is limited. In one cohort of Australian Vietnam veterans with PTSD, the incidence of psychotropic polypharmacy was reported as 33.1%, over double that of the general Australian population,¹⁶ whilst another smaller study in Australian veterans admitted to hospital for PTSD management reported a rate of 79.9%.¹⁷ However, these are studies of older Australian veterans, and less is known about polypharmacy rates in recently transitioned and contemporary ex-serving ADF veterans. With approximately 25% of recently transitioned ADF members estimated to meet the diagnostic criteria for PTSD in their lifetime,¹⁸ PTSD-related psychotropic polypharmacy is of significant concern.

This study aims to investigate the incidence of polypharmacy in a population of ADF veterans who utilised a medical service which assists service personnel in the transition from military to civilian life, and to illustrate potential risks associated with polypharmacy in this population.

Methods

Ethics statement

This study was approved by the Departments of Defence and Veterans’ Affairs Human Research Ethics Committee (DDVA HREC 554-23).

Design

A retrospective, observational cohort design was employed, utilising data obtained from the electronic medical records of individuals who accessed the services of a veteran-specific medical practice.

Participants

Participants were ADF veterans, aged over 18 years, who had first accessed the medical service between August 2021 and June 2024. Only data from individuals who had consented to use of their de-identified data for research purposes was collected.

Data collection

Data was extracted from medical records managed in Best Practice^© medical software. Admission forms were examined to ascertain whether individual consent was provided. Details were extracted from the patient’s initial presentation to the medical practice.

Variables included demographic data (age, gender, service branch, length of service, deployment history and level of education); documented psychological, physical and medical health conditions; and prescribed medications recorded on admission (medication type, indication, dose and frequency). Only broad drug classes were available (e.g. anti-hypertension medications and analgesics) in the dataset.

Statistical analysis

Medications were coded according to their Anatomical Therapeutic Chemical (ATC) Classification.¹⁹ To identify rates of polypharmacy, medications were separated into (a) Psychotropic N class (N05A Antipsychotics, N05B Anxiolytics, N05C Hypnotics and Sedatives, N06A Antidepressants, N06B Psychostimulants, Agents used for ADHD and Nootropics, N06C Psycholeptics and Psychoanaleptics in Combination), that is, psychotropic polypharmacy, (b) Other N Class medications, that is, ‘analgesic’ polypharmacy and (c) total counts of all concurrent medications (general polypharmacy) (i.e. including psychotropics, analgesics and all other non-N-class medications). Separation of the N class medications into two distinct groupings allowed more clinically meaningful analysis by distinguishing between medications used primarily for psychiatric conditions and those used for neurological or pain-related conditions.

The prevalence of psychotropic, other N class and general polypharmacy was calculated. General polypharmacy was defined as the concurrent use of ≥5 medications in total, while psychotropic and other N class polypharmacy was defined as the concurrent use of ≥2 psychotropic and other N class medications, respectively.¹⁷ We further stratified the sample by PTSD status to compare polypharmacy prevalence between veterans with and without PTSD using a chi-square test.

Logistic regression analysis was conducted to identify demographic factors associated with polypharmacy. Age, gender, marital status, deployment history, PTSD status, psychological, medical and musculoskeletal comorbidities were included as independent variables with psychotropic, other N class and general polypharmacy as dependent variables. Odds ratios (ORs) with corresponding 95% confidence intervals are reported to assess the strength and direction of associations.

Results

Participant characteristics

During the period of data extraction, 1310 veterans had given consent for use of their de-identified data. Only 1210 records provided full data requirements and were included in the analysis.

The cohort was predominantly male (80.8%), aged between 30 and 59 years (79.0%). Most participants were married (62.0%), and 297 (24.5%) had a diagnosis of PTSD (Table 1).

Table 1.

Participant characteristics (n = 1210)

Variable	Categories	n (%)
Sex	Male	978 (80.8)
Sex	Female	224 (18.5)
Age range	20–29	118 (9.8)
	30–39	322 (26.6)
	40–49	313 (25.9)
	50–59	321 (26.5)
	60–69	120 (9.9)
	≥70	17 (1.3)
Marital status	Married	750 (62.0)
	De facto	217 (17.9)
	Single	137 (11.3)
	Divorced	54 (4.5)
	Separated	38 (3.1)
	Widowed	4 (0.3)
Deployment history	War-like	756 (62.5)
	Non-war	72 (6.0)
	None	286 (23.6)
PTSD status	Yes	297 (24.5)
PTSD status	No	912 (75.4)

Comorbid conditions

Among veterans with PTSD, the most prevalent psychiatric comorbidities were depression (63.0%), anxiety (56.9%) and alcohol-use disorder (AUD) (31.3%). In veterans without PTSD, anxiety (27.3%) and depression (24.1%) were less prevalent, with lower rates of AUD (4.8%).

Medical comorbidities also differed between those with and without PTSD. Erectile dysfunction (25.6% vs 7.9%) and hypertension (15.2% vs 11.6%) were more frequent in those with PTSD. Musculoskeletal conditions were widespread in both groups, particularly chronic pain (PTSD = 35.4%, No PTSD = 34%), lumbar spondylosis (PTSD = 29.6%, No PTSD = 23%) and osteoarthritis (PTSD = 27.3%, No PTSD = 28.4%) (Table 2).

Table 2.

Top 5 comorbid conditions by PTSD status

Domain	Condition	PTSD (n = 297)	(%)	No PTSD (n = 912)	(%)
Psychiatric conditions	Depression	187	63.0	220	24.1
	Anxiety	169	56.9	249	27.3
	Alcohol-use disorder	93	31.3	44	4.8
	Adjustment disorder	44	14.8	66	7.2
	Insomnia/sleep disorder	7	2.4	13	1.4
Medical conditions	Tinnitus	77	25.9	213	23.4
	Erectile dysfunction	76	25.6	72	7.9
	Hypertension	45	15.2	106	11.6
	Hearing loss	59	19.9	132	14.5
	GORD	43	14.5	101	11.1
Musculoskeletal conditions	Chronic pain	105	35.4	210	23.0
	Lumbar spondylosis/back pain	88	29.6	215	23.6
	Osteoarthritis	81	27.3	259	28.4
	Rotator cuff syndrome	32	10.8	103	11.3
	Shin splints	29	9.8	71	7.8

Polypharmacy and medication use

General polypharmacy was present in 19.1% of the total cohort, psychotropic polypharmacy in 9.8% and other N-class polypharmacy in 14.6%. Veterans with PTSD were significantly more likely to experience psychotropic (25.9% vs 4.5%, p < .001) and general polypharmacy (33.7% vs 14.4%, p < .001) compared with those without PTSD. Rates of other N-class polypharmacy were modestly higher in veterans with PTSD (19.2% vs 13.2%, p = .035) (Table 3).

Table 3.

Polypharmacy prevalence

Type of polypharmacy	Absent n (%)	Present n (%)	χ² (df)	p-Value
General polypharmacy	979 (80.9)	231 (19.1)	54.3 (2)	<.001
Psychotropic polypharmacy	1092 (90.2)	118 (9.8)	117.0 (2)	<.001
Other N-class polypharmacy	1033 (85.4)	177 (14.6)	6.7 (2)	.035

The most frequently prescribed medications were paracetamol (20.9%), ibuprofen (15.1%) and esomeprazole (2.5%) (Table 4). Among veterans with PTSD, the most common psychotropics were escitalopram (11.8%), sertraline (11.4%) and quetiapine (7.7%), whereas veterans without PTSD were more commonly prescribed escitalopram (4.2%), sertraline (3.6%) and diazepam (1.5%) (Table 5).

Table 4.

Top five medications prescribed in the total cohort

Rank	ATC code	Drug name	n (%)
1	N02BE01	Paracetamol	792 (20.9)
2	M01AE01	Ibuprofen	571 (15.1)
3	A02BC05	Esomeprazole	93 (2.5)
4	M01AC06	Meloxicam	87 (2.3)
5	N06AB10	Escitalopram	73 (1.9)

Table 5.

Top five psychotropic agents by PTSD status

PTSD (n = 297)	n (%)	No PTSD (n = 912)	n (%)
Escitalopram (N06AB10)	35 (11.8%)	Escitalopram (N06AB10)	38 (4.2%)
Sertraline (N06AB06)	34 (11.4%)	Sertraline (N06AB06)	33 (3.6%)
Quetiapine (N05AH04)	23 (7.7%)	Melatonin (N05CH01)	18 (2.0%)
Melatonin (N05CH01)	22 (7.4%)	Diazepam (N05BA01)	14 (1.5%)
Duloxetine (N06AX21)	18 (6.1%)	Amitriptyline (N06AA09)	13 (1.4%)

Predictors of polypharmacy

Psychotropic polypharmacy

Psychiatric comorbidity was the strongest predictor of psychotropic polypharmacy, with each additional psychiatric condition nearly doubling the likelihood odds (OR = 1.91, 95% CI: 1.61–2.28, p < .001). Medical comorbidities contributed modestly to the likelihood of psychotropic polypharmacy (OR = 1.15, 95% CI: 1.02–1.29, p = .018). Importantly, PTSD was an independent risk factor, with veterans with PTSD having twice the odds of psychotropic polypharmacy compared with those without (OR = 2.07, 95% CI: 1.20–3.58, p = .009). No other factors were significantly associated (Table 6).

Table 6.

Logistic regression results for predictors of polypharmacy

Outcome	Predictor	OR (95% CI)	p-Value
Psychotropic polypharmacy	PTSD status (Y vs N)	2.07 (1.20–3.58)	.009
	Age (per 10 year category)	ns	.744
	Sex (F vs M)	0.74 (0.44–1.26)	.272
	Deployment type	ns	.971
	Psychiatric comorbidities	1.91 (1.61–2.28)	<.001
	Medical comorbidities	1.15 (1.02–1.29)	.018
	Musculoskeletal comorbidities	1.11 (0.97–1.28)	.130
Other N-class polypharmacy	PTSD status (Y vs N)	0.79 (0.49–1.29)	.349
	Age (per 10 year category)	↑ (trend: older age higher risk)*	.002
	Sex (F vs M)	0.77 (0.50–1.19)	.245
	Deployment type	ns	.805
	Psychiatric comorbidities	1.22 (1.06–1.41)	.005
	Medical comorbidities	1.16 (1.06–1.27)	.001
	Musculoskeletal comorbidities	1.08 (0.98–1.20)	.127
General polypharmacy	PTSD status (Y vs N)	1.16 (0.74–1.82)	.519
	Age (per 10 year category)	↑ (trend: older age higher risk)*	<.001
	Sex (F vs M)	0.62 (0.41–0.93)	.021
	Deployment type	ns	.567
	Psychiatric comorbidities	1.41 (1.22–1.62)	<.001
	Medical comorbidities	1.51 (1.37–1.66)	<.001
	Musculoskeletal comorbidities	1.02 (0.91–1.13)	.784

Notes: OR: odds ratio; CI: confidence interval; ns: not significant. * Age was included in models as categorical groups; results showed a clear increasing trend with age. Odds ratios for specific age bands are presented in the text.

Other N-class polypharmacy

Other N-class polypharmacy was driven by both psychiatric and medical comorbidities. Each additional psychiatric condition increased the odds by 22% (OR = 1.22, 95% CI: 1.06–1.41, p = .005), while each additional medical condition increased the odds by 16% (OR = 1.16, 95% CI 1:.06–1.27, p = .001). Age group was a strong predictor of other N-class polypharmacy (p = .002). Compared with the youngest veterans, those aged 40–49 (OR = 4.08), 50–59 (OR = 5.30) and 60–69 (OR = 13.99) had substantially elevated odds. Married participants had less N-class polypharmacy compared to other relationship categories (OR = 0.21, 95% CI: 0.07–0.64, p = .006). Musculoskeletal comorbidities, sex, deployment history and PTSD status were not significant predictors of N-class polypharmacy (Table 6).

General polypharmacy

General polypharmacy was most strongly associated with medical comorbidity. Each additional medical condition increased the odds by 51% (OR = 1.51, 95% CI: 1.37–1.66, p < .001), while each additional psychiatric condition increased the odds by 41% (OR = 1.41, 95% CI: 1.22–1.62, p < .001). Age group was highly predictive (p < .001), with increased odds among veterans aged 40–49 (OR = 3.80), 50–59 (OR = 5.91) and 60–69 (OR = 19.93) of taking ≥5 medications compared with the youngest age group. Females were less likely to experience general polypharmacy than males (OR = 0.62, 95% CI: 0.41–0.93, p = .021). Married participants had less polypharmacy compared to other relationship categories (OR = 0.42, 95% CI: 0.18–0.99, p = .046). Musculoskeletal comorbidities, deployment history and PTSD status were not significant predictors in this model (Table 6).

Discussion

This study examined polypharmacy rates in a cohort of ADF veterans transitioning to civilian life, with nearly one in five prescribed five or more medications concurrently. These rates are typically associated with older populations, despite most of this cohort being aged 30–50 years. This reflects the high burden of both psychiatric and physical comorbidities among recently transitioned veterans, often necessitating pharmacological management.^4,5 Concerningly, around one in ten veterans were concurrently prescribed multiple psychotropic medications, raising concerns about efficacy, safety and functional outcomes. Sedating or cognitively impairing medications can adversely affect attention-dependent activities and occupational functioning, underscoring the need to consider the broader functional impacts of polypharmacy, particularly during transition to civilian life.^12,13 Importantly, polypharmacy in this population can sometimes represent appropriate treatment of complex psychiatric and medical comorbidities,^4,20 but it still carries important risks including adverse effects, drug interactions and functional impairment.

The high prevalence of polypharmacy among these veterans with PTSD indicates that, even in a younger, contemporary cohort, polypharmacy is a significant clinical concern. The results reflect previous Australian and international findings, where PTSD consistently emerges as a driver of prescribing complexity.^15,16,21 It is rarely experienced in isolation and is frequently accompanied by depression, anxiety, AUD, and chronic pain.²² This clustering of conditions necessitates multidrug regimens, elevating the risk of drug–drug interactions and adverse effects.

Our results fill an important gap regarding polypharmacy in contemporary ex-serving ADF personnel. Previous Australian research had primarily documented polypharmacy in older or treatment-seeking veterans. The 33% psychotropic polypharmacy rate reported in Vietnam veterans with PTSD exceeds our 26% in PTSD, which is expected, given that cohort’s older age and chronic PTSD.¹⁶ Contrastingly, the high ∼80% psychotropic polypharmacy rate in an inpatient sample underscores how polypharmacy escalates with illness severity and healthcare setting.¹⁷ The moderate rates of polypharmacy in this cohort demonstrate that even recently transitioned, community-dwelling veterans with an average age around 45 experience notable polypharmacy. Polypharmacy risk may be higher in non-specialist and fragmented care settings, where less coordinated prescribing and single focus clinics (e.g. medicinal cannabis or ketamine services) can increase medication-related harm. The frequent prescription of paracetamol and ibuprofen in this cohort reflects the prevalence of chronic pain. Although evidence suggests that paracetamol and ibuprofen combinations may be used as an alternative to codeine-based analgesics for short-term pain management, they should not be used for more than a few days at a time and are not indicated for chronic pain management.²³ In the veterans with PTSD, the selective serotonin reuptake inhibitors (SSRIs), particularly escitalopram and sertraline, were the most commonly prescribed psychotropic medications. Although sertraline is recommended as a first-line drug for management of PTSD,²⁴ escitalopram is not a recommended approach and is only used off-label for PTSD. This may be because the ADF does not have to follow the recommended approach, and many veterans prescribed off-label treatment whilst in the ADF need to continue this after discharge. Quetiapine use was notable, yet it is only recommended as a third-line pharmaceutical option if both SSRIs and venlafaxine are not tolerated, or as adjunctive therapy if marked agitation is present.²⁴ Quetiapine may also cause drowsiness, an undesirable side effect in a younger population seeking employment during transition. Generally, the strength of evidence is too weak to recommend its use in PTSD.²⁵ Given its sedative and metabolic side-effect profile, this prescribing pattern may reflect a tendency towards use of augmentation strategies when first-line monotherapies have proven insufficient, reflecting the severity of PTSD in this cohort, and the long-term benefit versus harm of prescribed medications. Additional adverse side effects from medications such as olanzapine include weight gain, which can lead to secondary conditions such as obstructive sleep apnoea. This can render an individual unsuitable for occupations requiring sustained alertness, such as long-haul driving, piloting or train driving, adding greater challenges to finding employment. The use of medicinal cannabis (often used for chronic pain) was also observed in a proportion of this population and carries a secondary risk of worsening underlying psychiatric conditions.

Psychiatric comorbidity was the strongest predictor of psychotropic polypharmacy, consistent with prior research showing that increasing psychiatric multi-morbidity drives greater medication complexity, particularly in PTSD populations.^8,15 In contrast, the only modest effect of medical comorbidities reflects the fact that psychotropic prescribing is driven primarily by psychiatric complexity rather than general physical illness.

The pattern for other N-class polypharmacy differed. Both psychiatric and medical comorbidities were significant predictors, indicating that pain-related and neurological prescribing is influenced by both psychiatric and physical health complexity. This aligns with the recognised association between PTSD and chronic pain,⁶ where overlapping symptoms and functional impairment often lead to the concurrent use of analgesics, antidepressants or sedatives. Age had a strong effect in this domain with the highest odds observed among veterans aged 60–69, reflecting expected age-related increases in multi-morbidity, and aligning with broader pharmaco-epidemiologic literature showing that polypharmacy increases with age, even in non-geriatric veteran cohorts.²⁶ Being married was associated with significantly lower odds of other N-class polypharmacy. This may reflect the protective role of social support, which has been associated with lower psychiatric distress, better health management and reduced reliance on pharmacological interventions in veterans.¹⁴

For general polypharmacy, medical and psychiatric comorbidities were the strongest predictors, highlighting the cumulative impact of multi-morbidity across health domains.²⁷ Older age substantially increased the odds of general polypharmacy, mirroring trends in civilian and veteran populations world-wide.^15,28 In contrast, female and married veterans were significantly less likely to be on multiple medications. The reasons for this are unclear but may relate to sex differences in health-seeking behaviour and the stabilising role of marital support. PTSD was not a significant independent predictor of general polypharmacy, suggesting its impact operates primarily through increased psychiatric comorbidity and psychotropic medication use, rather than adding to the total number of medications.

This study has significant clinical implications. Transitioning veterans face not only multiple health challenges but also the added complexity of managing multiple medications. Systematic approaches to prescribing, including regular medication reviews, are essential to identify inappropriate or unnecessary polypharmacy and reduce the risks of adverse interactions. Equally important is greater integration of non-pharmacological strategies such as trauma-focused psychological therapies, pain rehabilitation and lifestyle interventions into veteran care. Development of veteran-specific prescribing guidelines could further assist clinicians in balancing therapeutic benefit with risk in this unique population.

Strengths of the study include the focus on a large, contemporary sample of transitioning veterans, a group underrepresented in Australian research. However, limitations must be acknowledged. The retrospective design restricted the availability of data on medication dose, duration and indication, and the single-site setting may limit generalisability. Additionally, the cross-sectional nature of the study precludes conclusions about prescribing trajectories or causal pathways linking PTSD, comorbidity and polypharmacy. The lack of a non-military comparator limits direct population comparisons and causal inference, but existing civilian literature suggests psychotropic polypharmacy rates are similar (12%) to those observed in transitioning veterans (9.8%).⁸ Future research should examine longitudinal trends in prescribing, including persistence of polypharmacy, de-prescribing practices and their impact on clinical and functional outcomes.

Conclusion

Polypharmacy is common among transitioning Australian veterans, predominantly driven by psychiatric and medical comorbidities, highlighting the need for targeted prescribing, structured medication review and integrated non-pharmacological care.

Footnotes

Acknowledgements

This study was funded by the Returned & Services League Queensland (RSLQ). We gratefully acknowledge Dr Pallavi Kalamkar for her contribution to the work in data extraction and de-identification.

ORCID iDs

Rebecca Mellor

Andrew Cronin

Sanket B. Raut

Ethical considerations

This study was approved by the Departments of Defence and Veterans’ Affairs Human Research Ethics Committee (DDVA HREC 554-23).

Consent to participate

Admission intake forms were examined individually to ascertain whether the participant had provided consent for use of their de-identified data for research purposes. Only records from participants who had provided consent were included in the analysis.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was funded by a grant from Returned & Services League of Australia, Queensland (RSLQ).

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

The data that support the findings of this study are not publicly available due to privacy and ethical restrictions. The data were derived from de-identified electronic medical records of veterans attending a veteran-focused medical service and were accessed under approval from the Departments of Defence and Veterans’ Affairs Human Research Ethics Committee (DDVA HREC 554-23). Due to the sensitive nature of the clinical data and governance requirements of the data custodians, the datasets cannot be shared.*

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