Health insurance status, lifestyle choices and the presence of non-communicable diseases: a systematic review

Abstract Background Although health insurance (HI) has effectively mitigated healthcare financial burdens, its contribution to healthy lifestyle choices and the presence of non-communicable diseases (NCDs) is not well established. We aimed to systematically review the existing evidence on the effect of HI on healthy lifestyle choices and NCDs. Methods A systematic review was conducted across PubMed, Medline, Embase, Cochrane Library and CINAHLComplet@EBSCOhost from inception until 30 September 2022, capturing studies that reported the effect of HI on healthy lifestyle and NCDs. A narrative synthesis of the studies was done. The review concluded both longitudinal and cross-sectional studies. A critical appraisal checklist for survey-based studies and the National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies were used for the quality assessment. Result Twenty-four studies met the inclusion criteria. HI was associated with the propensity to engage in physical activities (6/11 studies), consume healthy diets (4/7 studies), not to smoke (5/11 studies) or take alcohol (5/10 studies). Six (of nine) studies showed that HI coverage was associated with a lowered prevalence of NCDs. Conclusion This evidence suggests that HI is beneficial. More reports showed that it propitiated a healthy lifestyle and was associated with a reduced prevalence of NCDs.


Introduction
5][6] They account for 73% of mortality deaths globally, 7 of which most reported mortality could be prevented. 3,7NCDs are linked to four lifestyle risk factors: tobacco smoking, poor diet, physical inactivity and alcohol consumption. 4,8,91][12][13] A cohort study by Lv et al. 12 among Chinese adults has shown that about three out of four incidences of Type 2 diabetes could be avoided in <10 years with adherence to a healthy lifestyle.In a similar study in China, non-smoking, moderate alcohol intake, physical activity and a healthy diet were associated with lower risks of major coronary events and ischemic stroke. 11ealth insurance (HI) is a means to finance health care expenses by risk and resource pooling, 14,15 which is more likely to be efficient and equitable than the 'out-of-pocket' health payment method. 14The effect of HI on healthy lifestyle choices and health outcomes is not well established to date.The available evidences are inconclusive.Some studies claim HI increases the propensity to engage in a healthy lifestyle, [16][17][18] while others claim HI decreases the propensity to engage in a healthy lifestyle. 19,20In contrast, some studies found that HI does not affect healthy lifestyle choices and health outcomes. 21,22owever, there is a risk that HI may induce Ex-ante moral hazard.Ex-ante moral hazard occurs when HI reduces an individual interest in protective behaviours.Ex-ante moral hazard is not an intended outcome of HI 23 but a possible outcome of HI. 13,24 On the other hand, there could be a case of propitious selection where an individual purchases HI and still engages in a healthy lifestyle. 1This is a likely situation for people with high risk-averse who would like to avoid risk as much as possible.Ex-ante moral hazard could induce unhealthy lifestyles, precipitate NCDs related risk factors and subsequently lead to the incidence of NCDs.Considering the link between a healthy lifestyle and the incidence of NCDs, it is important to understand the effect of HI on lifestyle.
The primary aim of this systematic review is to review and summarize research that examined the effect of HI on healthy lifestyle choices and the presence of NCDs.This is to establish if HI is beneficial for healthy lifestyle choices and outcomes related to NCDs.This will provide information that can be used to develop effective policy reforms that can optimize HI plans.

Methods
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed for the systematic review.The protocol (Identification Number: CRD42021236377) was registered with the International Prospective Register of Systematic Reviews.Relevant studies were collected through electronic databases using predefined search terms and synonyms.
The search strategy is detailed in Appendix A. The following databases were searched: PubMed, Medline, Embase, Cochrane Library and CINAHLComplet@EBSCOhost. Alerts were created on the databases to notify new articles related to the search terms before the final analysis.Reference lists of eligible articles were searched for relevant literature.

Eligibility criteria
The established inclusion and exclusion criteria were used to screen identified articles for the review.The following study parameters were used to decide which studies to include: (i) population: studies that examined the adult population (from 18 years of age), (ii) intervention: studies that examine the effect of any HI scheme on at least one of the below outcomes, (iii) comparison: studies that compared HI with no insurance or other forms of insurance for studies with control conditions and (iv) outcome variables: the four major NCDs (cardiovascular diseases, cancer, chronic respiratory diseases and diabetes) and four major lifestyle-related risk factors (tobacco smoking, alcohol consumption, poor diet and physical inactivity identified by the World Health Organization 25 ).
Eligible studies included case-control, cohort studies, cross-sectional surveys and studies that reported quantitative data on the effect of HI schemes on at least one of the aforementioned outcome variables.The review included all studies from the inception of the selected databases until 30 September 2022.Only English articles were included.Abstracts, presentations, conference proceedings, unpublished data, letters to the editor, editorials and comments were excluded to avoid duplicate data and data that had not undergone peer review.

Data extraction
All searches were done by two reviewers (AF and MC).A third reviewer (TTS) was consulted on any disagreement.The selection of articles was conducted in three steps.In the first phase, articles were extracted from the selected database.Secondly, articles with titles not relevant to the study were excluded after screening for duplicates.In the third phase, articles were assessed for eligibility.
Endnote X6 was used to save and organize details of studies and screened for duplicates.The collected data were summarized into an extraction table.Whenever necessary, the authors of the included articles were contacted for more information.Five authors were contacted and three authors responded.

Quality assessment
A critical appraisal checklist for survey-based studies was used to assess the quality of the cross-sectional studies. 26he National Institutes of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was used to assess the longitudinal studies. 27Only good and fair (medium) quality studies were included in the study.The two assessment tools are attached in Appendix B. The quality assessment procedure is in Appendix C. The quality assessment grade is shown in Table 1.

Data synthesis
The reports were classified into three: (i) HI and healthy lifestyle: (a) physical activities, (b) smoking, (c) alcohol consumption and (d) healthy diets, (ii) HI and health outcomes related to NCDs and (iii) private HI versus other forms of HI status.We considered three possible effects: positive, negative Bittoni, et al. 39 -A greater proportion of the private insured reported a smoking history than the public/uninsured (58% versus 53%, P < 0.0001), while public/uninsured smokers have slightly more pack-years smoked.
Mean BMI was slightly higher for the privately insured group (P < 0.0001).
The privately insured group had a greater proportion of individuals classified with normal CRP levels < 3 mg/L (66% versus 57%; P < 0.0001), but also had significantly higher overall mean serum CRP levels (6.0 versus 4.5; P < 0.0001).
Overall, elevated CRP, smoking, reduced diet quality and higher BMI were more prevalent in those with public insurance and were associated with increased risks of cancer/chronic disease mortality Castillo-Laborde et al. 40 -Sixteen out of the 18 studied risk factors and disease prevalence were lower among private insurance beneficiaries, although the differences were insignificant after adjusting for age.
Dave and kaestner 20 -Medicare Being a Medicare beneficiary was associated with a 24% decrease in the likelihood of engaging in physical activity.This increased to 40% when controlled for doctor visits.
Medicare coverage is associated with a decrease in the number of cigarettes consumed daily without controlling for doctor visits.The association was small but statistically significant.(1.3%) Medicare is associated with a 31.8%(or 11.6% point) increase in the tendency for alcohol consumption among Medicare beneficiaries after controlling for doctor visits.
Although this association was not statistically significant.
In general, health insurance increased unhealthy lifestyles among the elderly.The probability of sedentariness increased significantly by 5.1% for individuals with URBMI than individuals with the Urban Employee Basic Medical Insurance.
Being a URBMI enrollee increased the likelihood of smoking by 1.2%, but this is not statistically significant.
The probability of using preventive care services, drinking alcohol/soft drinks, engaging in physical activity, and being overweight did not change significantly for URBMI insured Overall, URBMI did not change the utilization of preventive health care services, smoking/drinking habits, or other risky behaviours.However, the likelihood of being sedentary increased by 5% points.
(continued) ACA-Medicaid expansion was also associated with a lower HbAIc level.
No evidence of change in the cholesterol levels after ACA-Medical aid expansion.
In conclusion, there was improvement in two out of three cardiovascular risk factors accessed.
Hughes  34 -There was an increase of 1.01% per year in free-time physical activities among the insured.
Smoking prevalence decreased from 12.4% to 8.6% within a year among the population with private health insurance.
There was equally higher alcohol consumption for both insured and uninsured groups.
The consumption of fruits, legumes and vegetables increased at 0.72% per year.
The frequency of overweight and obesity increase by 1.53% and 0.95% per year, respectively, among the population with private health insurance.
No change in the prevalence of hypertension and diabetes among insured and uninsured but hypertension and diabetes were more frequent among people without private health insurance than the uninsured or those with other forms of insurance.
In general, the prevalence of risk factors was lower and the frequency of protective factors higher among privately insured compared with the uninsured.

Malta et al. 29
Not specified There was a decrease of 12.4 to 7.7% (P < 0.00) in the number of smokers from 2008 to 2015 among individuals with health insurance.
Recommended daily consumption of fruits and vegetables improved (24.9 to 30.9%; P < 0.00), but intake of excess fatty meat and consumption of beans did not change.
Regular consumption of soft drinks (five or more times a week) dropped.
Sufficient physical activity during leisure time increased from 35 to 43.9% (P < 0.00).
There was no change in sedentary and alcohol consumption indicators and driving after drinking.
The prevalence of self-reported hypertension and diabetes was less among the population with health insurance than those without health insurance.NRCMS increased the probability of smoking by 1.9%.(significant at the 10% level).
Participating in NRCMS increased the probability of smoking by 1.9%.
Being NRCMS participants encourage a daily high-calorie intake of 2180 kcal versus 2179.1 kcal in non-participants and decrease the percentage of healthy energy food consumption.NRCMS participants have a significantly higher tendency to be overweight than non-participants (27.4% versus 22%).

Sadarangani
et al. 38 Any health insurance Being insured contributed more to cardiovascular risk than other factors relating to health care access; it also increased the likelihood of being at risk of cardiovascular disease by 1.7 folds.
Stanciole 19 Any health insurance The insured tend to smoke more with a prevalence of 5% compared to 3% in the uninsured sample, drink more alcohol (8% versus 4%) and tend to be more sedentary (16% versus 11%).
The two groups fare very similarly in the prevalence of obesity (25% versus 26%).
y health insurance In general, undiagnosed and uncontrolled chronic illness was more frequent among the uninsured when compared to the insured.
Although undiagnosed hypertension was not associated with insurance status, the uninsured were more likely to have uncontrolled hypertension compared with insured individuals (42.0%versus 35%, P = 0.03) and no effects.The heterogeneity of the studies included in this review precluded a formal meta-analysis.

Results
A total of 27 796 articles were identified from the initial search.A total of 12 205 articles were excluded after screening for duplicates.A total of 15 591 articles were screened for relevance through their titles and abstracts, leaving 84 articles for further in-depth review.A total of 65 articles were excluded for various reasons, leaving 19 eligible articles, as shown in Figure 1.Eight additional articles were identified through other sources.Three articles were excluded for various reasons.The total eligible article was 24 (6 longitudinal and 18 cross-sectional studies).The summary characteristics of the included articles can be found in Table 1.

Effect of health insurance on physical activities
Eleven out of the 24 studies reported the effect of HI coverage on engaging in physical activities, comparing the insured with the uninsured.9][30] On the other hand, some studies 19,20,31,32 indicated that HI contributed to physical inactivity or the likelihood of adopting a sedentary lifestyle.One study by Miraldo et al. 21reported that HI has no effect on physical activity or the propensity to be sedentary.

Effect of health insurance on smoking
Eleven studies reported the effect of HI on smoking in comparative studies between the insured and uninsured.Five of these reports claimed HI reduces the propensity to smoke. 16,18,20,28,29Based on the studies by Malta and Bernal 28 and Malta et al . 16in Brazil, HI beneficiaries had a lower prevalence of smoking participants.Malta et al . 29lso reported a positive decrease in smoking prevalence among insured participants in Brazil.Dave and Kaestner 20 found that being a Medicare beneficiary is associated with a decrease in the number of cigarettes consumed daily without controlling for doctors' visits.The association was relatively small (1.3%) but statistically significant.The observation by Qin and Lu 30 was relatively different; they found that participating in the New Rural Cooperative Medical System (NRCMS) increased the probability of smoking by 1.9%.This is in line with the report by Stanciole. 19Four other reports claimed HI has no effect on the choice to smoke. 21,22,33n conclusion, more reports concluded that HI reduced the propensity to smoke as against no effect or increased effects.

Effect of health insurance on alcohol consumption
Ten studies examined the link between HI and alcohol consumption among insured and uninsured participants.Five of the 10 studies claimed HI did not encourage alcohol consumption, 16,19,[30][31][32] while one study claimed HI is associated with increased alcohol consumption. 20Four of the studies claimed HI does not affect alcohol consumption. 21,28,29,32tanciole, 19 in his report, stated that HI decreases the tendency for heavy drinking, while Decker et al . 32found binge drinking more common among uninsured participants.Malta et al . 16claimed alcohol use was at 17% (95%CI, 16.1-18.0)among people with HI but slightly higher among the uninsured group.In general, more reports concluded that HI has a positive effect on alcohol consumption as against negative or no effect.

Effect of health insurance on healthy diets
Seven studies examined the relationship between HI and diet among people with and without HI.Four of these studies suggested a positive link. 16,17,29,34The result published by Malta et al. 29 showed a positive increasing trend in fruit and vegetable intake.Malta et al. 16 found more frequent healthy diet indicators and less frequent unhealthy diet indicators in participants with HI than those without HI.The healthy diet indicators reported include sufficient intake of fruits and vegetables, which was at 30.9% (95%CI, 29.8-32.1)versus 19.8% (95%CI, 18.7-20.9)for the insured and uninsured, respectively.Two studies claimed HI is associated with poor diet. 30,31Qin and Lu 30 found that being NRCMS participants encouraged a daily high-calorie intake of 2180 kcal versus 2179.1 kcal in non-participants and decreased the percentage of healthy energy food consumption.One study claimed HI has no effect on diet. 21Overall, more reports concluded that HI encouraged a healthy diet.

Health insurance and health outcomes
Nine studies reported the impact of HI on health outcomes.6][37] Two reports indicated that HI has a negative effect on measured health comes 32,38 while one report states that HI has no effect on hypertension. 29he report by Wilper et al . 36stated that undiagnosed and uncontrolled chronic illness was more frequent among the uninsured when compared to the insured.Although undiagnosed hypertension was not associated with insurance status.Sadarangani et al . 38found that being insured contributed more to cardiovascular risk than other factors relating to healthcare access; it also increased the likelihood of being at risk of cardiovascular disease by 1.7 fold.In all, more reports associated HI with lowered prevalence of NCDs.

Private health insurance versus other forms of health insurance status
Three studies compared the effect of private HI schemes against other forms of HI on health behaviours or outcomes.All three studies reported better health outcomes and (or) behaviours with private HI compared to other insurance schemes. 33,39,40The study by Bittoni et al. 39 found that smoking, poor diet and raised C-reactive protein were more prevalent in people with public HI compared to the privately insured.Castillo-Laborde et al . 40found that risk factors and disease prevalence were lower among people with private HI.

Main findings
Twenty-four evaluations of the effect of HI on healthy lifestyle choices and (or) the presence of NCDs were identified.The results from these studies are mixed.However, most reports from these evaluations indicated HI encouraged healthy lifestyle choices.The most common health status measured are hypertension and diabetes.More reports concluded that HI was associated with a lowered prevalence of NCDs.Three evaluations on private HI were identified.All the evaluations found that private HI encouraged a healthy lifestyle.Furthermore, most of the studies on the effect of HI are cross-sectional-based.As stated earlier, the effect of HI on health-related outcomes are mixed, although most studies indicate that HI is beneficial.The variation in results could be related to the process of recruiting participants for the study.There is a high possibility of sampling bias since some HI coverage is guided by eligibility and availability, such as the Medicare scheme under the Affordable Care Act in the United States of America (USA). 32Similar to this is the NRCMS, a HI scheme subsidized by the government for rural residents in China. 30Hence, the samples pulled from the enrollee of the insurance scheme will not be a perfect representation of the population.The effect of HI from this sample is expected to differ from another study group where insurance enrolment is based on other eligibility criteria.Co-founding variables is another factor that could alter the measured impact or effect of HI on health-related outcomes.The presence of a co-founder could lead to under or over-estimation of the effect of HI.Dave and Kaestner 20 showed that the effect of being a Medicare beneficiary on physical activity increased when controlled for doctor visits.The effect of confounding variables should be vividly considered (if measurable) and reported when assessing the effect of HI.
HI is reported to have varying effects based on the country of study.In Brazil, people with HI coverage mostly make healthy lifestyle choices which are relatively different from the observation in the USA.The difference in observations in the USA and Brazil is not surprising, as both countries' healthcare systems differ.The USA has a less cost-effective multiplayer system when compared with its neighbouring Canada's singlepayer system. 41he USA HI industry is dominated by private HI schemes, which cover about 50% of Americans. 42The private HI schemes in the USA offer different premiums and packages 43 and most people get it from their employers and are sponsored by co-payment by both the employer and employee. 42The government, however, provides publicly funded insurance schemes for the elderly and people in the low-income group, known as Medicare and Medicaid, respectively, based on eligibility. 42Hence, the HI system in the USA is very competitive and beneficiaries are propelled to maximize their insurance benefit.This could potentiate extramoral hazards, where insurance beneficiaries tend to lose personal inducement to engage in a healthy lifestyle in lieu of HI benefits.
Unlike the USA, the Brazilian healthcare system is dominated by the public HI industry, similar to the healthcare system in Canada and the UK. 43Brazil has the largest populace with broad healthcare coverage globally, without incurring 'out-of-pocket' expenditure on healthcare users. 44This is achieved through the Sistema Único de Saúde, the unified health system launched in 1991. 45Other HI plans in Brazil include private HI, prepaid group practice and company health plans. 18Although most of the Brazilian population is covered under the Unified health system, 46 some people (those that can afford it) still opt for personal insurance.As of 2013, about 27.9% of Brazilians had private insurance plans. 47This is because the health system is faced with a shortage of resources 48 and enrollee would prefer personal HI to ensure timely access to healthcare.
The type of insurance determines the effect of HI.In most cases, private HI increases the likelihood of making a healthy lifestyle choice as opposed to other schemes.Although the articles reviewed in this study did not identify if the private HI schemes had integrated packages to induce healthy lifestyle choices.There are instances where HI providers promote healthy lifestyles among their clients by encouraging physical activity.This is mostly achieved by providing fitness centre offers.Furthermore, some insurers provide mobile devices to facilitate easy monitoring of diet, physical activity or sleep patterns.Clients who hit the mark of healthy living are rewarded monetarily with premium discounts or more.This is to improve clients' health and lower medical costs. 49This also serves as a check on ex-ante moral hazard.
Determining the effect of HI at a global level might be challenging.Accessing HI nationally is more feasible since most countries have unique HI structures.

21 - 4 ( 1 . 1 - 1 . 8 )
uninsured, health insurance beneficiaries were more likely to have protective factors, such as healthy eating, physical activity, coverage (mammography and Pap test), and lower risk factors such as smoking, physical inactivity, poor health assessment, and hypertension.Alcohol abuse, overweight, obesity, excessively fatty meats consumption and diabetes were not associated with health insurance status.Participants with health insurance generally have better indicators Miraldo et al.Increasing public subsidized health insurance did not affect behaviour risk factor or diabetes disease management except for alcohol intake in the lower-income white participant'with health insurance, women without health insurance were more likely to report physical inactivity (aRR = 1.1 (1.1-1.2)),smoking (aRR = 1.), and self-reported hypertension aRR = 1.4 (1.1-1.7))Qin and Lu 30 √ Rural Cooperative Medical Scheme (NRCMS) coverage in China decreased the probability of being sedentary at 95.1% versus 96% in the uninsured group.

Fig. 1
Fig. 1 PRISMA diagram (Flow of article search, screening, article assessment for exclusion and inclusion criteria with reasons for exclusion detailed).

Table 1
Summary characteristics of included articles

Table 2
Health insurance types and key findings