Valuing a Quality-Adjusted Life Year (QALY): willingness to pay among older adults in Iran

Abstract

Background

Willingness to pay (WTP) per quality-adjusted life year (QALY) is a monetary measure used to quantify how individuals value gains in health-related quality and quantity of life. Understanding this helps policymakers allocate healthcare resources efficiently, especially in aging societies with budget constraints. Measuring WTP clarifies the economic justification for life extension and the rationale for prioritizing end-of-life care. This study, examined the WTP for one additional QALY among older adults in Tehran and its influencing factors in 2024.

Methods

This cross-sectional study included 494 older adults selected through multi-stage cluster sampling from Tehran’s 22 districts and nursing homes. Data were gathered via interviews using a demographic checklist, a researcher-developed WTP questionnaire, and the validated EQ-5D-5 L instrument. Given the high likelihood of selection bias, the Heckman two-step method was employed to account for potential sample selection issues. Statistical analyses were performed in STATA 14.

Results

Participants were willing to trade 8.84 months of full healthy time for one year of their current life. The mean WTP for one QALY was USD3, 673 (1,969 million Iranian Rials, IRR), with half offering under USD 548 (294 million IRR). Based on Heckman method, retirees and homemakers had lower WTP, while higher education, income, and expenses increased it. Living in developed areas increased the likelihood of WTP, whereas religious commitment decreased it.

Conclusions

These findings provide a valuable reference for cost-effectiveness studies on interventions for older adults, enabling policymakers to assess the economic viability of allocating healthcare resources to this population. Furthermore, policymakers can consider the reasons behind older adults’ reluctance to invest in longer, healthier lives, which could inform targeted strategies to encourage greater investment in their health.

Background

Population aging, once a concern for developed nations, is now rapidly affecting developing countries, including Iran, which has one of the fastest-growing elderly populations worldwide [1, 2]. By 2031, the number of older adults in Iran is expected to double [3], Leading to a sharp rise in chronic diseases and increased use of health and aged care services [4]. This demographic shift has significantly increased healthcare costs, making aging a financial burden for many countries. The rise in chronic conditions among older adults results in higher mortality rates, reduced quality of life, greater dependency, and increased hospital admissions, all of which strain healthcare resources [5–7]. Given these challenges, the need for efficient resource allocation in healthcare has become more pressing [8].

Cost-effectiveness analysis, particularly using Quality-Adjusted Life Years (QALYs), provides a standardized framework for evaluating health interventions and supporting healthcare decision-making [9]. By incorporating both life expectancy and quality of life, QALYs enable comparisons across interventions and help identify strategies that generate greater health benefits relative to their costs [10, 11]. As a result, QALY-based evidence is widely used within economic evaluation to inform resource allocation decisions [12].

Assigning a monetary value to QALYs through willingness-to-pay (WTP) estimation offers insights into how individuals value gains in health and longevity [12–14]. Several approaches have been used to estimate willingness to pay for health gains, including contingent valuation, discrete choice experiments, and utility-based techniques linked to health-state preferences. Among these, the contingent valuation method is one of the most widely applied approaches for eliciting individuals’ monetary valuations of health improvements, as it allows respondents to express their maximum willingness to pay within specified hypothetical health scenarios [15]. In WTP per QALY studies, respondents are typically presented with hypothetical health-state descriptions and asked to value improvements in health or quality of life, allowing estimation of the monetary value individuals assign to health gains [16]. These estimates are increasingly used to inform economic evaluation and priority setting in healthcare, particularly in relation to cost-effectiveness and resource allocation decisions [17, 18].

In many health systems, cost-effectiveness thresholds are used to interpret WTP values, although their validity remains debated. The WHO-recommended threshold of one to three times GDP per capita is widely used as a reference. However, Iran has no formally adopted threshold, and economic evaluations generally rely on GDP-based benchmarks alongside contextual policy considerations [19–23].

Empirical studies on WTP per QALY have reported substantial variation across countries and populations. In Iran, Lankarani et al. [13] estimated the average WTP for one QALY at $2,847 or 0.57 times the national GDP per capita, with a higher willingness to pay among individuals in the final stages of life. Similarly, Moradi et al. [8] reported WTP estimates ranging from $1,032 to $2,666, representing 0.22 to 0.56 times GDP per capita, with income, education, and marital status significantly influencing WTP values. Ye et al. [24] found an average WTP per QALY of 1.75 times GDP per capita, emphasizing the impact of age, education, and mental well-being, particularly in reducing anxiety and depression. However, comparisons based on GDP-per-capita multiples should be interpreted cautiously in Iran, as GDP estimates rely on the official exchange rate and recent exchange-rate volatility has reduced the practical relevance of GDP-based thresholds. Moreover, existing estimates have largely been derived from general population samples, limiting their applicability to older adults with distinct health preferences and economic circumstances. Evidence suggests that older adults may value health gains differently due to shorter life expectancy, fixed income, and distinct health priorities compared with younger populations [25, 26]. Therefore, age-specific WTP estimates may provide additional insight for policy decisions involving resource allocation in older populations, particularly in interventions related to chronic disease and end-of-life care [27].

Given the rapid aging of Iran’s population and the growing burden of healthcare costs, understanding how older adults value health gains is particularly important. Evidence on WTP for QALYs among older adults can provide a better understanding of preferences related to health improvements in this population and contribute to discussions surrounding healthcare resource allocation [28]. Therefore, this study aims to estimate the monetary value of a QALY among Iranian older adults using a contingent valuation approach based on hypothetical health scenarios. The findings may provide context-specific evidence to support future economic evaluations and healthcare planning for the aging population.

Methods

Study design and setting

This cross-sectional study was conducted in 2024 among older adults residing in both community settings and nursing homes in Tehran, Iran. The study followed a chained approach for estimating WTP per QALY, adapted from Robinson et al. [29]. The chained approach combined health utility measurement, time trade-off (TTO), and contingent valuation techniques to estimate the monetary value that older adults assign to health gains.

The study was implemented in two sequential stages. First, participants’ current health-related quality of life was assessed using the EQ-5D-5 L questionnaire, and utility values were derived for each respondent [30]. Participants were then asked a time trade-off question to determine the amount of time they would be willing to exchange from one year of life in their current health state for a shorter period in full health. In the second step, a contingent valuation method was used to elicit individuals’ willingness to pay for improvements in health status. The payment vehicle was explicitly defined as direct personal expenditure. The time horizon was framed as gaining one additional year in full health compared with their current health state. Unlike the standard chained approach using fixed EQ-5D health-state vignettes, the valuation in this study was anchored to each respondent’s self-reported EQ-5D-5 L health status. Therefore, the size of the implied QALY gain varied across individuals. This approach allows respondents to value incremental improvements in health rather than large hypothetical health losses, thereby reducing cognitive burden and generating valuations that more closely reflect real-world preferences [31, 32].

Participants and sampling

Community-dwelling older adults

A multi-stage area sampling approach with proportional allocation was used across Tehran’s 22 districts. Within selected clusters, participants were recruited through convenience sampling from public locations such as parks, mosques, shopping centers, and community centers frequented by older adults. Data were collected through face-to-face interviews conducted by trained interviewers with expertise in gerontology, psychology, and social work. The sample size was determined based on the study by Jahanbin et al. [22], using the formula, (n = Z_(1−α/2)*SD/d)², with a confidence interval (CI) of 95% (α = 0.05), a standard deviation (SD) of 11.6, and a response rate adjustment of 10%. This calculation resulted in a final sample of 460 community-dwelling older adults. To account for socioeconomic diversity, Tehran’s 22 districts were stratified into five development categories according to Sadeghi et al. [33]. Two districts and two neighborhoods were randomly selected from each category. The number of participants from each region was determined based on the proportion of older adults residing in that area.

Nursing home residents

Nursing homes were classified into three socioeconomic strata (low, middle, and high SES), although low-SES facilities declined participation. Therefore, sampling was limited to middle- and high-SES institutions. Two facilities were randomly selected from each stratum, resulting in a sample of 34 residents. Although these facilities were located in higher SES areas, standardized admission policies allow residents from diverse socioeconomic backgrounds to reside in the same institutions; nevertheless, potential underrepresentation of residents from lower-SES settings should be considered when interpreting the findings.

Inclusion and exclusion criteria

The inclusion criteria for participation in this study included the following: informed and voluntary consent, age over 60 years, proficiency in Persian, ability to communicate verbally and auditory, and the absence of mild cognitive impairment (MCI). The assessment for MCI was conducted using the Mini-Cog test. The Persian version of Mini-Cog is a user-friendly and acceptable cognitive test for Persian-speaking older adults. The study by Rezaei et al. [34] showed that the sensitivity and specificity of the Mini-Cog test were 0.88 and 0.62, respectively. This study demonstrated that the words and instructions of this test could be clearly understood and were acceptable to the participants. Furthermore, this study highlights the suitable face validity of the Persian version of the Mini-Cog [34]. Exclusion criteria encompassed any participants who expressed unwillingness to continue with the interview process, as well as those who were unable to proceed due to unforeseen physical health issues.

Measures

Demographic and socioeconomic variables

A structured checklist was used to collect data on marital status, educational attainment, place and type of residence, occupation, household and personal income, living arrangements, health insurance coverage, chronic diseases, tobacco use, independence status, quality of life, and physical and mental disabilities.

WTP Questionnaire for QALY

The WTP questionnaire was developed by the research team using the contingent valuation method to estimate respondents’ monetary valuation of health gains. Before the valuation exercise, participants were asked whether they could recall or imagine a period in their lives during which they considered themselves completely healthy and free from disease or functional limitations. If the participant answered affirmatively, this self-defined state was used as the respondent’s ideal health state for subsequent valuation questions.

Participants were then presented with hypothetical treatment scenarios. They were asked to assume that a treatment was available that could restore them from their current health condition to their ideal health state. Respondents were subsequently asked to indicate the maximum amount they would personally be willing to pay out-of-pocket to obtain such treatment and achieve one additional year in ideal health. A similar question was asked for a five-year period in ideal health to explore the effect of the duration of health gains on WTP.

The questionnaire consisted of five items addressing the respondent’s perception of ideal health, expected duration of life in ideal health, willingness to pay for one additional year in ideal health, willingness to sell major assets to obtain health-improving services, and willingness to pay for five additional years in ideal health. The face validity of the study instruments, particularly the contingent valuation scenarios, was assessed qualitatively through expert review. Experts evaluated the clarity, relevance, and appropriateness of the hypothetical health-state descriptions and WTP questions, and provided feedback to ensure conceptual consistency and contextual suitability. In addition, cognitive feedback was obtained from older adults during the pilot phase (n = 18), leading to minor revisions in the wording of several CV scenarios to improve comprehensibility and ensure that questions were easily understood by the target population. Test-retest reliability was assessed in 25 participants over a two-week interval, showing good stability (ICC = 0.79).

EQ-5D-5 L questionnaire

The EQ-5D-5 L is a standardized instrument developed by the European Quality of Life Organization to measure health-related quality of life. It evaluates five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The Iranian validation study reported satisfactory convergent validity (correlation coefficients ranging from 0.37 to 0.60) and good test–retest reliability for the EQ-5D-5 L index (ICC = 0.85) [35].

A TTO exercise was conducted to quantify the value participants placed on improvements in health status. Respondents were asked to compare one year of life in their current health state with a shorter period of life in full health and indicate the maximum amount of time they would be willing to forgo in exchange for living in complete health. The TTO responses were used to estimate health utility gains associated with a transition from the current health state to full health and formed part of the chained approach used to calculate WTP per QALY.

Statistical analysis

Data were analyzed using STATA version 14. Descriptive statistics were reported as mean and standard deviation (SD) for continuous variables and frequency (percentage) for categorical variables. The normality of continuous variables was assessed using the Kolmogorov–Smirnov test, along with skewness and kurtosis statistics. Independent-sample t-tests, one-way analysis of variance (ANOVA), and correlation analyses were used to examine bivariate associations.

To identify factors associated with WTP, binary logistic regression models were estimated, where the dependent variable was whether the respondent expressed a positive willingness to pay for health improvement (yes/no). Because a proportion of respondents reported zero WTP, a two-step Heckman selection model was additionally employed to examine factors associated with the amount of WTP while accounting for the selection process underlying the decision to pay. All monetary values were collected and analyzed in Iranian Rials (IRR) and were subsequently were converted to US dollars using the official exchange rate of the Central Bank of Iran (Currency Exchange and Gold Center) for 2024, set at 536,000 IRR per USD.

No missing data were observed because all questionnaire items were completed during interviewer-administered interviews. Participants who were unable to understand the valuation tasks or complete the interview process were excluded in accordance with the study exclusion criteria. Statistical significance was set at p < 0.05.

Ethical considerations

The Ethics Committee in Research of the University of Social Welfare and Rehabilitation Sciences approved the study protocol (Approval No. IR.USWR.REC.1402.218). All procedures involving human participants were conducted in accordance with the ethical standards of the institutional research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Written informed consent was obtained from all participants prior to data collection.

Results

This study included 494 older adults residing in both community dwellings and nursing homes, with a mean age of 68.39 (SD ± 6.48) years (Table 1). The majority were male (54.05%) and had less than a high school diploma (42.31%). Nearly 44.13% were retired, 33.00% lived with their spouses, and 18.2% lived alone. Social security insurance coverage was reported by 43.32% of participants. The mean monthly income was 258 (SD ± 180) million IRR. Among chronic conditions, hypertension had the highest prevalence (34.2%), while cancer had the lowest (3.4%).

Table 1.

Characteristics of participants

Variable	Frequency	Percent
Sex
Female	226	45.95
Male	267	54.05
Marital status
Married	330	66.80
Single (widowed, divorced, never married)	164	33.20
Living arrangements
Living alone	90	18.22
With children and spouse	156	31.58
With spouse	163	33.00
With others	47	9.51
In nursing home	38	7.69
Education
Illiterate	67	13.56
Under high school diploma	209	42.31
High school diploma	130	26.32
Associate degree and Bachelor's	71	14.37
Postgraduate degree	17	3.44
Employment Status
Employed	52	10.53
Retired	218	44.13
Retired but employed	44	8.91
Housewife	180	36.44
Having caregiver(s)
yes	52	10.53
No	442	89.47
Medication Use
yes	398	80.57
No	96	19.43
Daily Activities
Employed and socially active	168	34.08
Independent but not working	262	53.14
Partially dependent	29	5.88
Fully dependent	34	6.90
Insurance Coverage
Social Security	214	43.32
Private Supplementary Insurance	17	3.44
No Insurance	56	11.34
Full Insurance	207	41.90
Internet Usage
Less than 30 minutes	61	12.35
One hour	90	18.22
More than an hour	115	23.28
not use	228	46.15

Based on a single-item assessment, 69.6% of older adults rated their health status as 6 or higher on a 10-point scale. In contrast, less than 1% of participants rated their health as 1, indicating the poorest status. Another single-item question revealed that less than 1% of seniors reported having no religious beliefs, while approximately 86% expressed moderate religious beliefs. Among the participants, about 29% demonstrated strong religious commitment, reflecting complete adherence to their faith.

According to the time trade-off approach, older adults were willing to forgo 8.84 months of their remaining life in exchange for one additional year of healthy life (QALY). The average (median) amount they were willing to pay for one extra QALY was approximately 1,969 (294) million IRR, equivalent to USD 3,673 (USD 548) based on the official exchange rate. However, the large standard deviation indicated considerable variability, suggesting that at least half of the respondents were willing to pay less than this amount. Figure 1 presents the average WTP across selected demographic groups. Women, employed participants, married older adults, and those with higher educational attainment reported higher mean WTP than their respective counterparts. These descriptive findings suggesting that socioeconomic position and educational achievement may be associated with greater valuation of health gains among older adults.

Fig. 1.

Willingness to pay for a QALY among demographic groups (Million IRR)

Determinants of willingness to pay

The study found that 71.8% of older adults were willing to pay for treatment to restore their full health, but only 37.8% were willing to sell major assets for this purpose. Logistic regression analysis showed no significant gender differences in WTP, though women exhibited slightly higher willingness. Age was negatively associated with WTP, with older individuals demonstrating lower willingness. Residents of highly developed areas in Tehran had significantly higher WTP than those in moderately developed areas, while no significant differences were observed in lower-development areas.

Employment status was a key factor, as housewives had lower WTP than employed older adults, likely due to financial dependence. However, retirees and working retirees showed no significant differences in WTP. Living arrangements, including residence in nursing homes, did not significantly impact WTP. Income, whether individual or household, was not significantly associated with the likelihood of expressing a willingness to pay for health improvement. This finding suggests that the decision to report a positive WTP may be influenced by factors beyond financial resources alone. Nevertheless, an important question remains as to whether income affects the probability of reporting WTP or the magnitude of WTP among those willing to pay. The Heckman model was further used to examine these two aspects separately. Religious beliefs, however, had a significant effect on WTP, indicating that stronger religious convictions decreased willingness to pay, possibly due to differing perspectives on life and health. Health status had a negative but non-significant effect, suggesting that healthier individuals may feel less urgency for healthcare spending (Table 2).

Table 2.

The results of logit regression analysis

Variable	Coefficient	z	p-value
Sex (Reference: Male)
Female	0.52	1.01	0.31
Age group (Reference: Young Older Adults)
Old Adults	0.06	0.23	0.82
Oldest-Old Adults	-0.08	-0.15	0.88
Residential Area (Reference: Moderately Developed Area)
Highly developed Area	1.31	2.83	0.005
Developed Area	0.98	2.27	0.02
Less developed Area	0.19	0.38	0.70
Underdeveloped Area	0.36	0.72	0.47
Employment Status (Reference: Employed)
Retired	-0.71	-1.26	0.20
Retired but working	-0.44	-0.67	0.50
Homemaker	-1.56	-2.17	0.03
Living arrangements (Reference: Living Alone)
Living with Spouse and Children	-0.32	-0.75	0.45
Living with Spouse	-0.21	-0.57	0.56
Living with Children or Others	0.05	0.11	0.91
Nursing Home Resident	0.44	0.38	0.70
Insurance coverage (Reference: No Insurance)
Social Insurance (Pension and Basic Health Coverage)	-0.29	-0.62	0.53
Private Insurance	0.33	0.34	0.73
Comprehensive Insurance	-0.33	-0.67	0.50
Income	0.01	1.49	0.13
Self-Reported Religious Commitment	-0.16	-2.74	0.006
Self-Rated Health Status	-0.08	-1.2	0.22
Constant Term	2.9	2.81	0.005

In this study, alongside logistic regression, the two-step Heckman model was employed to address potential selection bias, as some participants reported zero willingness to pay, and improve the robustness of the results. While logistic regression helped identify the factors associated with whether individuals are willing to pay, the Heckman model allowed us to further investigate the factors influencing the amount of willingness to pay. In this approach, the outcome equation examined determinants of the monetary amount of WTP among respondents who expressed a positive willingness to pay, whereas the selection equation identified factors associated with the likelihood of reporting a positive WTP. By including significant variables from the logistic regression in the first stage of the Heckman model, we ensured that the analysis accounted for both the likelihood of willingness to pay and the magnitude of that willingness, providing a more comprehensive understanding of the factors at play.

The findings indicate that employment status significantly affects the amount of WTP. Compared to employed individuals, retirees demonstrate a significantly lower WTP (β = -198.12, p = 0.01), while homemakers and those retired but still working also have lower WTP, though not statistically significant. Education level was positively associated with the amount of WTP. Compared with illiterate participants, respondents with postgraduate education demonstrated substantially higher WTP values, indicating a greater monetary valuation of health gains among more highly educated older adults (β = 460.65, p = 0.005). However, lower levels of education do not show significant effects. Economic resources were important determinants of the amount of WTP. Both personal income (β = 1.86, p = 0.01) and household expenditures (β = 2.68, p = 0.004) were positively associated with higher WTP values, suggesting that among those willing to pay, greater financial capacity translated into larger monetary valuations of health improvements. Notably, different types of insurance coverage do not have significant effects on WTP, indicating that having insurance does not necessarily increase the amount individuals are willing to invest in additional years of quality life.

Second step in The Heckman results indicate the factors associated with having or not having a willingness to pay for one additional QALY. Residential area influences the likelihood of having WTP. Compared to those living in moderately developed areas, individuals residing in highly developed (β = 0.69, p = 0.01) and developed areas (β = 0.56, p = 0.03) are significantly more likely to express WTP. However, those from less developed or underdeveloped areas do not show statistically significant differences. Self-reported religious commitment (β = 0.005, p = -2.81) has a significant negative effect, suggesting that individuals with stronger religious beliefs may be less inclined to express WTP for life extension. Employment status does not significantly impact the likelihood of WTP, as the coefficients for retirees, homemakers, and those retired but working are not statistically significant.

The estimated correlation between the error terms of the two equations was negative but not statistically significant (rho = -0.27, p = 0.17), suggesting limited evidence of selection bias. Similarly, the inverse Mills ratio coefficient was small, indicating that the amount of WTP was not substantially affected by the selection process. Nevertheless, the Heckman framework allowed separate examination of the determinants of WTP participation and WTP amount, providing additional insight into valuation behaviour among older adults (Table 3).

Table 3.

Heckman’s two-stage model

	Variable	Coefficient	t-statistic	p-value
Amount of Willingness to pay	Employment Status (Reference: Employed)
	Retired	-198.12	-2.34	0.02
	Retired but working	-157.04	-1.46	0.14
	Homemaker	-127	-1.42	0.15
	Educational Attainment (Reference: Illiterate)
	Less than high school diploma	73.75	1.13	0.25
	High school diploma	75.69	1.02	0.30
	Associate degree	38.55	0.42	0.67
	Bachelor degree	134.07	1.14	0.25
	Master’s degree and PhD	460.65	2.83	0.005
	Insurance coverage (Reference: No Insurance)
	Social Insurance (Pension and Basic Health Coverage)	55.65	0.80	0.42
	Private Insurance	-29.44	-0.23	0.82
	Comprehensive Insurance	-68.87	-1.00	0.31
	Monthly household expenses	2.68	2.9	0.004
	Personal monthly income	1.86	3.54	0.001
	Fixed coefficient	231.87	2.24	0.02
Having a willingness to pay	Residential Area (Reference: Moderately Developed Area)
	Highly developed Area	0.69	2.49	0.01
	Developed Area	0.56	2.14	0.03
	Less developed Area	0.60	0.21	0.83
	Underdeveloped Area	0.11	0.38	0.70
	Employment Status (Reference: Employed)
	Retired	-0.29	-0.9	0.36
	Retired but working	-0.29	-0.74	0.45
	``Homemaker	-0.45	-1.4	0.16
	Self-Reported Religious Commitment	-0.09	-2.81	0.005
	Constant Term	1.11	2.55	0.01
	athrho	-0.28	-1.35	0.17
	lnsigma	5.70	98.71	0.01
	Rho	-0.27
	sigma	299.31
	lambda	-83.72

As a sensitivity analysis, an ordinary least squares (OLS) regression was conducted among respondents with a positive willingness to pay. The direction and statistical significance of the main predictors remained largely consistent with the Heckman outcome equation. The only notable difference was that the association between personal monthly income and WTP amount was attenuated and became marginally non-significant in the OLS model. Overall, the findings suggest that the main conclusions were robust across alternative modeling approaches.

Discussion

This study aimed to assess WTP for QALYs and its determinants among older adults in Iran. The average WTP for one QALY was estimated at 1,969 million IRR (USD 3,673), corresponding to 0.28 times Iran’s GDP per capita in 2023. This estimate is substantially lower than that reported by Moradi et al. [32] for the Iranian general population, suggesting that older adults may assign a lower monetary value to additional health gains than younger populations. Studies conducted in East and Southeast Asia generally report higher WTP values for health gains than those observed in the present study. For example, Shiroiwa et al. [36] in Japan reported an average WTP of approximately USD 50,000 per QALY, while Ha et al. [37] found that most Vietnamese respondents were willing to pay at or above the national GDP per capita threshold. These studies suggest that higher income levels, broader health insurance coverage, and differences in social expectations regarding healthcare financing may contribute to higher valuations of health gains. In contrast, the lower WTP observed among Iranian older adults may reflect the combined effects of economic instability, reduced purchasing power, and the fixed-income nature of many older adults.

This study found that 71.8% of older adults willing to pay for a treatment that improve their quality of life, but economic constraints and personal preferences were significant factors influencing their decisions. Only 37.8% were willing to sell major assets for treatment, reflecting financial limitations or conservative attitudes toward asset preservation. Demographic factors such as age, marital status, and education significantly influenced WTP. Younger old individuals exhibited greater WTP, likely due to more optimistic health outlooks and longer life expectancies. While no significant differences were found between middle-aged and older groups, data showed a decrease in WTP as age increased. However, age did not significantly impact WTP for QALYs, potentially because the perceived value of QALYs may be similar across different age groups. This aligns partially with the findings of Fernandez et al. [38], who observed an 18% decrease in WTP per decade of life, and other studies that confirmed age’s negative correlation with WTP [24, 39]. Some studies, such as Pinto et al. [14], suggest that older adults generally exhibit lower WTP for QALYs compared to the general population, which could be due to focusing exclusively on older individuals. Conversely, Ha et al. [37] reported higher WTP among older patients, and Huang et al. [40] found that older individuals demonstrated a higher WTP compared to other groups. In addition, the considerable proportion of zero WTP responses underscores the value of the Heckman two-step model. By separating the decision to pay from the amount willing to be paid, this approach recognizes that zero responses may reflect not only financial constraints but also preferences related to ageing, family responsibilities, and healthcare expectations. This distinction provides a more nuanced understanding of health valuation in later life and helps reduce bias in WTP estimates.

In our study, which specifically targeted older adults, no significant gender differences in WTP for QALYs were observed. In contrast, Moradi et al. [41] reported a significant gender effect, with women exhibiting higher WTP than men. This discrepancy may be attributed to the unique characteristics of the older adult population, where gender roles and economic responsibilities might differ from those in the general population. Additionally, variations in societal, economic, and cultural contexts across studies [38, 42] could contribute to these inconsistent findings. Some research suggests that, in broader populations, men may be more inclined to invest in health-related expenses due to their traditional provider roles [37]. The lack of a significant gender difference in WTP for QALYs among older adults suggests that gender-related economic and social role distinctions may diminish in later life, as individuals face more convergent financial constraints and shared health priorities. Consequently, WTP for health gains in older age may be more strongly shaped by universal late-life conditions than by gender-specific roles or responsibilities.

This study found that older adults in highly developed areas of Tehran were more willing to pay for QALYs compared to those in moderately developed areas. These results align with economic theories suggesting that more developed regions have greater financial access and awareness of quality of life [43].

Employment status was found to be a significant predictor of WTP. Housewives, who tend to be financially dependent, had lower WTP, while retirees also exhibited lower WTP, likely due to fixed income and different attitudes toward health expenditures. This finding aligns with previous studies, which generally report that employed individuals are more likely to have higher WTP for health-related expenses [37, 40, 44].

An important finding of this study concerns the different roles of income in the decision to pay versus the amount paid. The binary regression models indicated that neither personal nor household income significantly influenced whether an older adult expressed a willingness to pay for health improvement. However, the Heckman model revealed that among respondents who were willing to pay, both personal income and household expenditures were positively associated with the amount of WTP. This suggests that financial resources may play a limited role in determining whether older adults value additional health gains, but become increasingly important when determining how much they are able or willing to contribute financially. Higher-income individuals may not perceive healthcare costs as urgently as those with lower incomes, which contrasts with some studies that found a positive correlation between income and WTP for healthcare [37, 45]. While income is a significant factor in WTP for the general population, the influence of income on WTP among older adults may be diminished by factors such as dependence on household income, the fixed nature of retirement income, and the prioritization of family support systems. The use of the Heckman selection model provided additional insight beyond conventional binary regression analyses. By separately examining the decision to report a positive WTP and the amount of WTP, the model highlighted that different mechanisms may underlie these two processes. While economic variables were more strongly associated with the magnitude of WTP, factors such as personal values, perceptions of aging, and religious commitment appeared more relevant to the initial decision of whether to express a willingness to pay at all. This distinction would have been less visible if respondents with zero WTP had simply been excluded from the analysis.

Living arrangements also did not significantly affect WTP in this study. This contrasts with studies by Shiroiwa et al. [36] and Moradi et al. [8], which indicated that living with a spouse positively influenced WTP. This result suggests that, for older adults, the financial and emotional support from family members, as well as access to public or institutional healthcare services, may outweigh the direct influence of where they live. Therefore, it is important to consider a more holistic approach when analyzing WTP among older adults, taking into account the various sources of support that may influence their healthcare decisions.

Educational attainment was significantly associated with higher WTP for QALYs. Individuals with higher education levels exhibited a stronger willingness to pay, consistent with studies suggesting that education enhances awareness, understanding of health importance, and financial capability [21, 32, 46]. Additionally, the study found a negative, but non-significant, relationship between religious beliefs and WTP, suggesting that individuals with stronger religious convictions may prioritize health decisions differently. Religion has been widely recognized as a key cultural determinant of health attitudes across societies, shaping perceptions of illness, mortality, and healthcare behavior [47, 48]. However, given the non-significant association observed in this study, the findings should be interpreted cautiously. Several theoretical mechanisms may still be relevant. Religious fatalism or beliefs in divine control may reduce perceived individual agency in health-related financial decisions. Similarly, beliefs in an afterlife may alter the perceived value of additional life years, while interpretations of suffering as meaningful or predetermined may increase acceptance of illness and influence how health gains are economically valued [15].

Health status had a negative but non-significant effect on WTP. One possible interpretation is that healthier individuals may perceive less urgency for additional health interventions, as they already feel well and therefore might not see substantial benefit in investing further in their health. This perspective is consistent with the findings of Shiroiwa et al. [36] but contradicts the findings of Huang et al. [40] and Fernandez et al. [38], who found a stronger correlation between health status and WTP for full health restoration. These discrepancies could be due to differences in sample characteristics or cultural contexts; for instance, in populations where individuals experience more acute health challenges, the perceived need for health restoration might be more pronounced, leading to a higher willingness to invest in health improvements.

In this study, older people living in the community-dwelling and in nursing homes centers participated, which can be considered a strength of the study compared to other studies. Although this study endeavored to minimize methodological, ethical, and environmental constraints, research limitations are an inherent aspect of the research process. Consequently, the present study was not immune to these limitations and included several constraints. Some nursing homes were excluded from our study because all of their residents suffered from severe cognitive impairment. Some older individuals in the centers lacked accurate information regarding their own and their families’ income status. Older women were less inclined to participate in the study compared to men, primarily due to their limited knowledge of household income.

Conclusions

The findings of this study reveal that the willingness to pay for a QALY among older adults in Tehran is significantly lower than the benchmarks suggested by the World Health Organization. However, the WTP value for QALYs was much lower, indicating that older adults in Iran are less willing to invest in additional years of healthy life. This low WTP suggests a gap between the perceived value of health and the actual financial commitment older adults are willing or able to make for improved health outcomes.

These findings suggest that a single cost-effectiveness threshold may not adequately capture the heterogeneity of health preferences across individuals with different socioeconomic and cultural characteristics, particularly among older adults. They also highlight the limitations of relying on GDP-based thresholds in settings such as Iran, where official exchange rates may not reflect underlying economic conditions and where repeated exchange-rate shocks have reduced the practical relevance of conventional threshold benchmarks. Based on these findings, several policy directions can be considered. First, targeted financial support mechanisms such as subsidizing or partially covering cost-effective QALY-generating interventions for older adults could reduce affordability barriers and improve access to essential health services. Second, incorporating age-sensitive or equity-informed adjustments into cost-effectiveness decision frameworks—such as exploring age-weighted societal preferences in threshold setting—may better reflect the value placed on health in older populations. Third, public health and educational campaigns aimed at improving awareness of the benefits of preventive care and health investment in later life may help strengthen informed health-related decision-making among older adults. Furthermore, the influence of religious beliefs on WTP suggests that cultural and ethical considerations should be integrated into policy discussions on end-of-life care investments. Policies that enhance the economic security of older adults, particularly those who rely on pensions or family income, could help raise their willingness to invest in health interventions.

Abbreviation

CV

Contingent Valuation

GDP

Gross Domestic Product

IRR

Iranian Rials

MCI

Mild Cognitive Impairment

QALY

Quality-Adjusted Life Year

SES

Socio-Economic Status

TTO

Time Trade Off

USD

United States Dollar

WTP

Willingness to Pay

WHO

World Health Organization

Authors’ contributions

MB, ZA, ZKh, PKh, MS, and AI contributed to the study’s design. ZA and FH collected data. MB performed statistical analyses. MB and ZA wrote the draft of the manuscript. All authors reviewed the manuscript.

Funding

Not applicable’ for that section.

Data availability

The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The Ethics Committee in Research has approved the protocol for this study at the University of Social Welfare and Rehabilitation Sciences under the code IR.USWR.REC.1402.218. Participants provided informed consent before data collection.

Consent for publication

Not applicable’ for that section.

Competing interests

The authors declare no competing interests.