Chronic pain, defined as pain that persists for more than 3 months(Reference Treede, Rief and Barke1), is among the most common chronic conditions and leading causes of disability in the USA(Reference Mokdad and Ballestros2). Over 20 % of US adults suffer from chronic pain and up to half of those (7–10 % of US adults) report high-impact chronic pain, defined as pain that frequently limits life and work activities(Reference Rikard, Strahan and Schmit3,Reference Yong, Mullins and Bhattacharyya4) . Alarmingly, the proportion of US adults reporting pain and painful health conditions has been on the rise(Reference Grol-Prokopczyk5–Reference Zajacova, Grol-Prokopczyk and Zimmer7). While chronic pain frequently co-occurs with an underlying disease, it is also recognised as an independent condition(Reference Treede, Rief and Barke1,Reference Clauw, Essex and Pitman8) .
Chronic pain is a highly complex and multidimensional condition, with dynamic interplays of biological, psychological, behavioural, sociocultural and environmental factors contributing to its development and progression(Reference Cohen, Vase and Hooten9–Reference Patel, Johnson and Booker11). Certain population subgroups are especially vulnerable to chronic pain, particularly older adults and those who experience socio-economic disadvantages(Reference Mills, Nicolson and Smith10). Notably, much of the heterogeneity in the epidemiology of chronic pain can be explained by socio-economic factors, such as income and education(Reference Rikard, Strahan and Schmit3,Reference Grol-Prokopczyk5,Reference Zajacova, Grol-Prokopczyk and Zimmer7,Reference Dahlhamer, Lucas and Zelaya12) . As such, the influence of socio-economic factors on chronic pain, and vice versa, is an increasingly important area of investigation, and further research on mechanisms underlying socio-economic disparities in chronic pain is needed.
Food insecurity is recognised as a social determinant of health with overwhelming evidence linking it to an increased burden of chronic diseases and mental health disorders(Reference Gregory and Coleman-Jensen13–Reference Laraia15). Food insecurity refers to limited or uncertain access to sufficient nutritious foods. It may be the result of financial constraints, limited availability of food choices (e.g. food deserts) or difficulties accessing food (e.g. lack of transportation). Food insecurity is not to be confused with hunger, a physiologic condition that may result from severe food insecurity. According to the US Department of Agriculture (USDA), 10·2 % of US households (13·5 million) experienced food insecurity during 2021(Reference Coleman-Jensen, Rabbitt and Gregory16). Food insecurity affects some of the most vulnerable individuals in the USA and has the potential to influence many of the factors that contribute to chronic pain. Notably, the impact of food insecurity on health outcomes is often independent of, additive to, and/or greater than other socio-economic risk factors, such as low income(Reference Gregory and Coleman-Jensen13,Reference Laraia15,Reference Men, Fischer and Urquia17) . On the other hand, food insecurity may be more modifiable than other socio-economic factors, for instance, through food assistance programmes.
Despite the growing recognition of food insecurity as a significant risk factor for many of the most prevalent public health concerns(Reference Gregory and Coleman-Jensen13), relatively little attention has been given to the potential link between food insecurity and chronic pain. A growing body of evidence has associated food insecurity with an increased risk of pain(Reference Men, Fischer and Urquia17) and pain-related emergency room visits(Reference Men, Urquia and Tarasuk18) in Canada. In the USA, one study observed that 53 % of food bank users reported chronic pain(Reference Bigand, Dietz and Gubitz19). However, population-based studies of chronic pain and high-impact chronic pain in relation to food insecurity in the USA are lacking.
Given the immense public health burden of chronic pain and the potential link with food insecurity, this study evaluated the relationship between food insecurity and chronic pain among US adults using US population-based data. We also evaluated the relationship between food insecurity and high-impact chronic pain, a US National Pain Strategy and Healthy People 2030 priority due to its interference with and limiting impact on people’s lives.
Methods
Study design and population
This cross-sectional study utilised pooled data from the 2019–2021 National Health Interview Survey (NHIS)(20) to investigate the relationship between food insecurity and chronic pain. The NHIS is a nationally representative household survey of the US civilian non-institutionalised population residing within the fifty states and the District of Columbia. The NHIS is conducted annually by the National Center for Health Statistics (NCHS), which is part of the Centers for Disease Control and Prevention (CDC). A detailed description of the NHIS sampling methodology and data collection procedures is available on their website (https://www.cdc.gov/nchs/nhis/index.htm). Participants with missing or invalid data (refused, not ascertained, don’t know) on food security or pain were excluded from this study (n 2946). A flow chart for inclusion and exclusion of participants can be seen in Fig. 1.
Fig. 1 Participant flow chart
Food insecurity
The ten-item US Adult Food Security Survey was used to measure food security status in the past 30 d(Reference Coleman-Jensen, Rabbitt and Gregory16). Based on the number of affirmative responses, participants were classified as having high (0), marginal (1–2), low (3–5) or very low food security (6–10). These categories correspond to the following constructs, as defined by the USDA:
-
High food security: no indications of food-access problems or limitations.
-
Marginal food security: some anxiety over food sufficiency, with little or no indication of changes in diets or food intake.
-
Low food security: reduced quality, variety, or desirability of diet, with little or no indication of reduced food intake.
-
Very low food security: multiple indications of disrupted eating patterns and reduced food intake.
Regarding the use of food assistance programmes, participants were asked whether they had received Supplemental Nutrition Assistance Program (SNAP) benefits, formerly known as ‘food stamps’, in the past 12 months (yes, no).
Chronic pain and related outcomes
The primary outcome of this study was the presence of chronic pain. Participants were asked: ‘In the past three months, how often did you have pain? Would you say never, some days, most days, or every day?’ Chronic pain was defined as having pain ‘most days’ or ‘every day’ in the past 3 months(Reference Rikard, Strahan and Schmit3,Reference Yong, Mullins and Bhattacharyya4) . The presence of high-impact chronic pain among the subset of participants who reported chronic pain was a secondary outcome of this study. Participants who reported pain at least ‘some days’ were also asked: ‘Over the past three months, how often did your pain limit your life or work activities? Would you say never, some days, most days, or every day?’ Participants classified as having chronic pain who also reported limiting pain ‘most days’ or ‘every day’ were classified as having high-impact chronic pain(Reference Rikard, Strahan and Schmit3). This question was not fielded during the first and second quarters of the 2020 NHIS, thus it is missing in a subset of participants (n 3251) who reported chronic pain during the 2020 NHIS but were not asked about high-impact pain.
Additional explanatory variables
Both food insecurity and chronic pain are highly complex, multifactorial issues associated with several shared social, behavioural, psychological and biological factors. We therefore adjusted for potential confounding factors, including sociodemographic variables: age (18–44, 45–64 and ≥ 65 years), sex (male and female), race/ethnicity (Hispanic, non-Hispanic (NH) White, NH Black/African American, NH Asian and other), household size (1 adult, ≥ 2 adults; no children and ≥ 1 child), marital status (married, widowed, divorced or separated, never married, living with a partner), US veteran (yes and no); socio-economic: US citizenship (yes and no), US native (yes and no), educational attainment (less than high school, high school or equivalent, some college, bachelor’s degree or higher), household income (< 100 %, 100 to < 200 %, 200 to < 400 %, ≥ 400 % of federal poverty level (FPL)), employment (employed, not employed but worked previously and never worked), health insurance (private, Medicaid and other public coverage, other coverage, and uninsured), US geographical region (Northeast, Midwest, South and West), urbanisation (large central metro, large fringe metro, medium and small metro, and non-metropolitan); and clinically relevant factors: smoking (never, current smoker and former smoker), BMI (BMI, underweight (< 18·5 kg/m2), healthy weight (18·5–24·9 kg/m2), overweight (25·0–29·9 kg/m2) and obesity (≥ 30·0 kg/m2)), and diagnosis (yes, no) of: arthritis, asthma, cancer, CHD, chronic obstructive pulmonary disease/emphysema/chronic bronchitis, hypertension, diabetes, myocardial infarction, stroke, dementia, anxiety and depression. Previous studies using NHIS data have reported on the relationship between these factors and the prevalence of chronic pain and/or high-impact chronic pain(Reference Rikard, Strahan and Schmit3,Reference Dahlhamer, Lucas and Zelaya12,Reference Pitcher, Von Korff and Bushnell21,Reference Zelaya, Dahlhamer and Lucas22) .
Statistical analysis
Sample characteristics are presented by food security status as number of participants and weighted percentages. Differences between levels of food security (high, marginal, low and very low) were tested with Rao–Scott chi-square test. Weighted logistic regressions for chronic pain and high-impact chronic pain were performed, adjusting for the complex survey design (i.e. stratified cluster sampling), sampling weights provided by the NHIS, and year of survey to estimate adjusted OR and 95 % CI. Multivariable logistic regression models were also performed in order to adjust for additional explanatory variables, including sociodemographic, socio-economic and clinically relevant factors, as well as SNAP participation. Trend tests for food insecurity were conducted by treating food insecurity as an ordinal variable in the multivariable logistic regression model. We also explored potential interaction effects between food insecurity and significant covariates. Results were considered statistically significant at P < 0·05. The data analysis for this paper was generated using SAS software, version 9.4 of the SAS System for Windows. Copyright © (2013) SAS Institute Inc. SAS and all other SAS Institute Inc. product or service names are registered trademarks or trademarks of SAS Institute Inc., Cary, NC, USA.
Results
Sample characteristics
Sample characteristics can be found in Table 1. The analytic sample consisted of 79 686 US adults of ages 18–44 (45·8 %), 45–64 (32·5 %) and ≥ 65 (21·6 %) years. Overall, participants were 51·6 % female, 63·4 % NH White, 11·5 % NH Black and 16·6 % Hispanic. Most participants lived in households of ≥ 2 adults (81·5 %), were a US citizen (91·7 %), and US native (81·6 %) and lived in urban areas (86·1 %). Ten per cent of participants fell under the FPL for household income, while 41·5 % had incomes of 400 % or higher. Over a third of participants had a high school level education or lower (38·5 %). Most participants were overweight (33·2 %) or had obesity (31·9 %) with a wide range of chronic health conditions ranging from history of stroke (2·8 %) to hypertension (31·2 %). Additionally, 16·6 % and 15·2 % reported a diagnosis of depression and anxiety, respectively.
Table 1 National Health Interview Survey (NHIS) 2019–2021 participants’ characteristics by food security level*
NH, non-Hispanic; FPL, federal poverty level; GED, General Educational Development; COPD, chronic obstructive pulmonary disease; SNAP, Supplemental Nutrition Assistance Program.
* Percentages shown are adjusted for complex survey design and NHIS sampling weights. Column percentages may not aggregate to 100 per cent.
† Annual household income is reported as a percentage of the FPL.
Food insecurity
In total, 13·3 % of participants reported some level of food insecurity, with 5·8 %, 4·4 % and 3·1 % reporting marginal, low and very low food security, respectively. Additionally, 11·8 % of participants reported receiving SNAP benefits with a higher proportion among food-insecure participants, ranging from 31·5 % to 44·3 % between those with marginal and very low food security, compared with 7·9 % among those with high food security.
Food insecurity and chronic pain
A total of 21·1 % of participants reported chronic pain. The prevalence of chronic pain was incrementally higher as the severity of food insecurity increased (Fig. 2). Compared with 19·2 % among adults with high food security, the rates of chronic pain for marginal, low and very low food security were 27·3 %, 35·0 % and 44·4 %, respectively. Indeed, food insecurity was associated with increased risk of chronic pain at all levels and a significant dose–response effect (P < 0·0001 for trend); see Table 2. Compared with high food security, the odds of chronic pain were 1·58 (95 % CI 1·44, 1·72), 2·27 (95 % CI 2·06, 2·52) and 3·37 (95 % CI 3·01, 3·78) for those with marginal, low and very low food security, respectively. These relationships remained consistent, although the effect size was attenuated, after adjustment for covariates: 1·28 (95 % CI 1·14, 1·42), 1·55 (95 % CI 1·37, 1·75) and 1·90 (95 % CI 1·65, 2·18) for marginal, low and very low food security, respectively.
Fig. 2 (a) Chronic pain by food security level (n 79 686). (b) High-impact chronic pain by food security level in adults with chronic pain (n 15 243)
Table 2 Associations between food insecurity and chronic pain
aOR, adjusted OR; NHIS, National Health Interview Survey.
Bolded values denote statistical significance at P < 0·05.
* Model 1 is adjusted for complex survey design, NHIS sampling weights and survey year.
† Model 2 is additionally adjusted for age, sex, race/ethnicity, household size, household income, marital status, US-born, US citizenship, US veteran status, education, employment, health insurance, urban/rural residence, US region, smoking, BMI, arthritis, asthma, cancer, CHD, chronic obstructive pulmonary disease/emphysema/chronic bronchitis, high cholesterol, hypertension, diabetes, myocardial infarction, stroke, dementia, anxiety, depression and SNAP participation (also known as ‘food stamps’).
Food insecurity, particularly at the levels of low and very low food security, showed a stronger association with chronic pain than other socio-economic factors, such as household income (aOR: 1·32 (95 % CI 1·17, 1·48) for income < 100 % FPL compared with ≥ 400 % FPL), education (aOR: 1·11 (95 % CI 1·00, 1·24) for ‘less than high school’ compared with ‘bachelor’s degree or higher’), employment (aOR: 1·26 (95 % CI 1·18, 1·35) for ‘not employed, worked previously’ compared with employed) and rural residence (aOR: 1·07 (95 % CI 0·98, 1·17) compared with large central metro). The full model with estimates for all the independent variables can be found in online supplementary material, Supplemental Table 1.
The relationship between food insecurity and chronic pain is modified by SNAP and age
We also explored potential interaction effects between food insecurity and covariates that were found to be significantly associated with chronic pain. There was a significant interaction effect between food insecurity and SNAP participation on chronic pain (P = 0·015). To better illustrate this effect, in Table 3, we show the association of food insecurity and chronic pain stratified by SNAP participation. Among SNAP non-participants, all levels of food insecurity were associated with chronic pain. However, among SNAP participants, only very low food security was associated with chronic pain, but not marginal and low food security levels. Additionally, we found a significant interaction effect between food insecurity and age (P < 0·0001), as shown in Table 4. Whereas all levels of food insecurity were associated with chronic pain among 18–64-year-olds, only low and very low food security (not marginal food security) remained significantly associated with chronic pain in older adults.
Table 3 SNAP use modifies the association of food insecurity with chronic pain and high-impact chronic pain
SNAP, Supplemental Nutrition Assistance Program; NHIS, National Health Interview Survey.
Bolded values denote statistical significance at P < 0·05.
* P-value for food insecurity*SNAP participation interaction term.
† OR and 95 % CI are adjusted for age, sex, race/ethnicity, household size, household income, marital status, US-born, US citizenship, US veteran status, education, employment, health insurance, urban/rural residence, US region, smoking, BMI, arthritis, asthma, cancer, CHD, chronic obstructive pulmonary disease/emphysema/chronic bronchitis, high cholesterol, hypertension, diabetes, myocardial infarction, stroke, dementia, anxiety, depression, as well as complex sampling design, NHIS sampling weights and survey year.
Table 4 Age modifies the association of food insecurity with chronic pain and high-impact chronic pain
SNAP, Supplemental Nutrition Assistance Program; NHIS, National Health Interview Survey.
Bolded values denote statistical significance at P < 0·05.
* OR and 95 % CI are adjusted for sex, race/ethnicity, household size, household income, marital status, US-born, US citizenship, US veteran status, education, employment, health insurance, urban/rural residence, US region, smoking, BMI, arthritis, asthma, cancer, CHD, chronic obstructive pulmonary disease/emphysema/chronic bronchitis, high cholesterol, hypertension, diabetes, myocardial infarction, stroke, dementia, anxiety, depression, SNAP participation, as well as complex sampling design, NHIS sampling weights and survey year.
† P-value for food insecurity*age interaction term.
Food insecurity and high-impact chronic pain
Over a third (35·0 %) of participants who reported chronic pain (and were asked about high-impact pain) also reported high-impact chronic pain. As seen previously, there was a direct correlation between the severity of food insecurity and high-impact chronic pain prevalence (Fig. 2, Table 2). Compared with 30·9 % among adults with high food security, the rates of high-impact chronic pain for marginal, low and very low food security were 43·4 %, 52·2 % and 56·4 %, respectively. Compared with high food security, the odds of high-impact chronic pain in relation to marginal, low and very low food security were 1·71 (95 % CI 1·44, 2·03), 2·44, (95 % CI 2·04, 2·88) and 2·89 (95 % CI 2·41, 3·43), respectively; P-trend < 0·0001. After adjustment for covariates, these effect sizes were attenuated but remained significantly associated with high-impact chronic pain (aOR: 1·24 (95 % CI 1·01, 1·52), 1·47 (95 % CI 1·21, 1·79) and 1·70 (95 % CI 1·38, 2·09) for marginal, low and very low food security, respectively, as compared with high food security). Similar to chronic pain, food insecurity showed a stronger association with high-impact chronic pain than other socio-economic factors, except for employment (aOR: 2·16 (95 % CI 1·47, 3·17) for ‘not employed, never worked’ and 2·47 (95 % CI 2·19, 2·79) for ‘not employed, worked previously’ as compared with employed); see online supplementary material, Supplemental Table 1.
The relationship between food insecurity and high-impact chronic pain is modified by SNAP and age
In the effect modification analyses, we found a significant interaction effects between food insecurity and SNAP participation (P < 0·0001) and age (P < 0·0001) on high-impact chronic pain. Among SNAP non-recipients, all levels of food insecurity were associated with high-impact chronic pain (Table 3). On the other hand, among SNAP recipients, only low and very low food security, but not marginal food security, remained significantly associated with high-impact chronic pain. With regard to age (Table 4), food insecurity was not associated with high-impact chronic pain among 18–44-year-olds. Among individuals aged 45–64 years, low and very low food security, but not marginal food security, were associated with high-impact chronic pain. Among participants ≥ 65 years old, only very low food security was associated with high-impact chronic pain.
Discussion
This study evaluated the relationship between food insecurity and chronic pain in a large representative sample of US adults using pooled data from the 2019–2021 NHIS. The results suggest that food insecurity is a significant risk factor for chronic pain and high-impact chronic pain, independent of and with a stronger association than other socio-economic risk factors, such as income and education. Moreover, the odds of chronic pain and high-impact chronic pain increased in accordance with the severity of food insecurity, with individuals experiencing very low food security having the highest risk compared with those with high food security. These findings illustrate the impact of food insecurity as an important socio-economic factor that may influence chronic pain. The results regarding high-impact chronic pain, defined by frequent limitations to an individual’s life and work, are of particular importance and public health relevance. Indeed, reducing the prevalence of high-impact chronic pain is an objective within the US National Pain Strategy and Healthy People 2030. Interestingly, our findings also suggest that food assistance programmes (i.e. SNAP) may have a beneficial impact on chronic pain and high-impact chronic pain among individuals with marginal levels of food insecurity. Further research on socio-economic determinants of chronic pain is warranted, as well as the consideration of food insecurity in the clinical assessment of pain and pain-related conditions among socio-economically disadvantaged adults.
As shown in this study and others, over 20 % of US adults have chronic pain(Reference Rikard, Strahan and Schmit3). Our findings show a disproportionately high prevalence of chronic pain among the food-insecure population, with over a third (33·8 %) of food-insecure adults (those with at least marginal food security) reporting chronic pain. In comparison, the age-adjusted prevalence of chronic pain among individuals living under the FPL is 28·8 %(Reference Rikard, Strahan and Schmit3). Our findings add to previous reports by Men et al. showing that food insecurity was associated with pain(Reference Men, Fischer and Urquia17) and pain-related emergency room visits(Reference Men, Urquia and Tarasuk18) in the Canadian population. Similar to the present study, the investigators found a dose–response association between the severity of food insecurity and the odds of chronic pain and pain that prevents most activity in a nationally representative sample of the Canadian population(Reference Men, Fischer and Urquia17). Moreover, in both studies, the odds of pain outcomes in relation to food insecurity were markedly higher than other socio-economic factors, such as income and education. Our results may be more conservative than those by Men et al., as their study defined chronic pain as being ‘usually free of pain or discomfort’ rather than the temporal criterion of 3 months or longer as developed by the International Association for the Study of Pain (IASP)(Reference Treede, Rief and Barke1). Additionally, the Canadian Community Health Survey uses a modified version of the US Household Food Security Survey and differences in the implementation and classification of food insecurity lead to underestimation of food insecurity in the USA as compared with Canada(Reference Men and Tarasuk23).
Given that food insecurity affects over 10 % of US households(Reference Coleman-Jensen, Rabbitt and Gregory16), the intersection of food insecurity and chronic pain represents a significant public health challenge. Of particular concern is the impact of food insecurity on older adults, a rapidly growing population group that is disproportionately affected by chronic pain(Reference Rikard, Strahan and Schmit3) and is vulnerable to food insecurity and compromised nutritional status(Reference Bernstein and Munoz24–Reference Reid26). Interestingly, we observed a modifying effect of age on the relationship between food insecurity and chronic pain. Among adults aged 18–44 years, food insecurity was associated with higher odds of chronic pain, but not high-impact chronic pain. This may be partly due to high-impact chronic pain being most predominant among adults 45 years of age and older(Reference Rikard, Strahan and Schmit3,Reference Pitcher, Von Korff and Bushnell21) .
Yet, in older adults, only low and very low food security were associated with chronic pain or high-impact chronic pain, suggesting that older adults may be less susceptible to the impact of marginal levels of food insecurity on their burden of chronic pain. Nevertheless, the strength of the association between low/very low food security and pain outcomes was higher for older adults than for younger adults. The interaction between food insecurity and age may reflect that older adults in the USA are particularly vulnerable to severe food insecurity when living alone(Reference Coleman-Jensen, Rabbitt and Gregory16), and that the prevalence of chronic pain, especially high-impact chronic pain, rises dramatically with age(Reference Rikard, Strahan and Schmit3,Reference Pitcher, Von Korff and Bushnell21) . It may also reflect currently unknown factors including interactions with other socio-economic factors not measured in our study. Further research is needed to comprehend the complex interplay between food insecurity, age and chronic pain.
There are several potential mechanisms by which food insecurity may influence chronic pain, all of which relate to the complex interplay between shared social, behavioural and biological factors. Among these, food insecurity contributes to poor quality diets and maladaptive eating patterns that compromise nutritional status(Reference Larson, Laska and Neumark-Sztainer27–Reference Leung and Wolfson29). Thereby, food insecurity potentially exacerbates proposed mechanisms underlying the impact of nutrition on chronic pain, including malnutrition, obesity, inflammation, metabolic dysfunction and nervous system sensitisation, among others(Reference Elma, Brain and Dong30,Reference Elma, Yilmaz and Deliens31) . Notably, food insecurity has been associated with markers of systemic inflammation(Reference Gowda, Hadley and Aiello32), as well as diets with higher inflammatory potential(Reference Bergmans, Palta and Robert33), which in turn have been associated with incidence of pain in middle-aged and older adults(Reference Carballo-Casla, Garcia-Esquinas and Lopez-Garcia34,Reference Liu, Hebert and Shivappa35) .
The current study’s findings also suggest that SNAP participation may beneficially modify the association of food insecurity with chronic pain. Formerly known as the Food Stamp Program, SNAP is the largest food assistance programme in the USA. Yet, there has been limited research examining its impact on health outcomes. Promising findings include better self-reported health(Reference Gregory and Deb36), and reduced hospital admissions, healthcare costs, and mortality(Reference Berkowitz, Palakshappa and Rigdon37,Reference Heflin, Ingram and Ziliak38) . On the other hand, SNAP participants demonstrate poorer quality diets and higher likelihood of metabolic syndrome when compared with non-participant peers(Reference Fang Zhang, Liu and Rehm39,Reference Gleason, Hansen and Wakar40) . Although most eligible individuals participate in the programme (78 % in 2020)(Reference Vigil41), many SNAP recipients remain food-insecure even after receiving benefits(Reference Bleich, Moran and Vercammen42,Reference Carlson, Llobrera and Keith-Jennings43) . Furthermore, the current criteria for eligibility, such as having a gross income below 130 % of the poverty line, prevent many individuals from obtaining SNAP benefits(Reference Bleich, Moran and Vercammen42). More research is needed to evaluate how food assistance programmes may play a role in lessening the burden of food insecurity, including its impact on chronic pain.
It is important to note that the relationship between food insecurity and chronic pain is likely bidirectional. Pain (and analgesic medications) can lead to loss of appetite and other gastrointestinal complications that compromise dietary intake and nutritional status. Similarly, chronic pain can lead to significant physical and functional limitations affecting the ability to secure food, particularly among older adults(Reference Coleman-Jensen44). Inability to work and pain-related healthcare costs can result in financial hardships that contribute to food insecurity. Indeed, data from the 2011 NHIS showed that 83 % of participants with high-impact chronic pain were unable to work outside of the home(Reference Pitcher, Von Korff and Bushnell21). Moreover, an analysis of the 2008 Medical Expenditure Panel Survey showed that chronic pain places a significant burden on the US economy, comprised of healthcare costs and reduced worker productivity, totalling between $560 and $635 billion annually(Reference Gaskin and Richard45). This relationship may create a vicious cycle between chronic pain and food insecurity that leads to the deterioration of health and quality of life. Therefore, there is a need for improved interventions to secure access to sufficient nutritious foods among socio-economically disadvantaged groups, especially those who are subject to disability due to their pain.
Strengths and limitations
The use of 2019–2021 NHIS data and its chronic pain supplement is a strength of this study, as the NHIS is the primary source of pain surveillance in the USA and the questions have been specifically designed based on IASP criteria for chronic pain and high-impact chronic pain. Additionally, the US Household Food Security Survey – used by the USDA to monitor food insecurity in the US population annually – is the most widely used and validated assessment of food insecurity(Reference Carrillo-Álvarez, Salinas-Roca and Costa-Tutusaus46). On the other hand, this instrument does not entirely capture the experience of food insecurity, trading comprehensiveness for simplicity(Reference Jones, Ngure and Pelto47). There may be factors unaccounted for in this analysis that may help explain the relationships seen in this study, such as dietary quality and structural barriers to food access or health care, among others. The COVID-19 pandemic may have influenced the results of the study. For one, the NHIS transitioned from primarily in-person to telephone interviews during 2020 and part of 2021. While NHIS weighing procedures minimise coverage and non-response bias, some measurement biases remain. Additionally, the early stages of the COVID-19 pandemic saw a temporary rise in food insecurity within the USA(Reference Kim-Mozeleski, Pike Moore and Trapl48), although, overall, the prevalence of food insecurity in the USA remained stable during 2019–2021(Reference Coleman-Jensen, Rabbitt and Gregory16). While the cross-sectional study design does not allow for causality to be established, the dose–response effect between the severity of food insecurity and the odds of chronic pain suggests that food insecurity may at least partially contribute to chronic pain. Nevertheless, a bidirectional relationship is possible. For instance, longer episodes of chronic pain may lead to more severe disability and financial strains that contribute to more severe food insecurity.
Conclusion
Food insecurity may be a social determinant of chronic pain among US adults. Food assistance programmes may provide a beneficial impact with regard to chronic pain among people with marginal levels of food insecurity. Further studies are needed to better understand the complex and temporal relationship between food insecurity and chronic pain and to identify targets for interventions. The findings of this study illustrate the impact of food insecurity on chronic pain based on cross-sectional analyses. Studies are needed using longitudinal designs to further explore how food insecurity may influence chronic pain over time. Furthermore, the consideration of socio-economic factors such as food insecurity in the clinical assessment of pain and pain-related conditions among socio-economically disadvantaged adults may be warranted.
Acknowledgements
We would like to thank the staff of the National Center for Health Statistics for their contributions to the National Health Interview Survey.
Financial support
Research reported in this publication was supported by the National Institute on Aging (T32AG049673, K99AG081552, R01AG059809, R01AG067757, R01AG076082 and P30AG028740) and the National Center for Advancing Translational Sciences (5UL1TR001427–06) of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Authorship
J.A.T. designed research and wrote initial version of manuscript; J.A.T. and S.D.K. performed statistical analyses; L.J.S., A.L.S., K.T.S., S.A. and Y.C.A. critically revised the manuscript. J.A.T. had primary responsibility for final content. All authors read and approved the final manuscript.
Conflict of interest
The authors have no conflicts of interest to declare.
Ethics of human subject participation
This study was exempt from Institutional Review Board review because the study utilised de-identified, publicly available datasets.
The data that support the findings of this study are openly available at https://www.cdc.gov/nchs/nhis/data-questionnaires-documentation.htm.
Supplementary material
For supplementary material accompanying this paper visit https://doi.org/10.1017/S1368980023002732
Open access
