Although health inequalities have most often been documented in wealthy countries, recent studies have made it evident that inequality in health and health care is also a prominent problem in developing countries [28, 34–36]. In particular, analysis of the effect of health care is especially important in those countries, where resource limitations require that the effective use of all health interventions be made.
The results of the present study show the existence of significant socioeconomic inequalities in health services utilization. The rate of outpatient services utilization is higher among individuals who have private health insurance and higher level of education. Furthermore, the analysis shows social gradients in opposite directions: the less educated have the largest proportion of poor self-rated health but are the ones with lower utilization rate. Following the inverse care law , use of care varies inversely with the needs of the population served.
In Brazil, the association between utilization rate and socioeconomic status has been shown before [38, 39], and is partly explained by the influence of private health plan coverage, since persons with private health insurance have shown higher odds of utilizing health care services . Another factor is the limited capacity of public outpatient services to meet the demand of health care [41–43].
In relation to differences in health service utilization by sex, higher percentages of service utilization were found among women. Gender differences in health care utilization are well-known. In general, studies that address morbidity and health services utilization have found that women report more symptoms than men, have worse perception of health status, and are more likely to use medical care .
Our findings indicate a consistent association between the use of outpatient services and health care need, as individuals reporting poor health were more likely to use health care, corroborating results from other studies [45–47]. Yet, it is important to note that more than a quarter did not use an outpatient service in the preceding year despite reporting a fair or poor self-rated health, or having unmet health care needs. This issue deserves specific attention as studies have related unmet health care needs with an increase in mortality risk .
In regard to the association between socioeconomic status and health services utilization, according to self-rated health status, the analysis shows that the weaker the need, the sharper the socioeconomic gradient in health services utilization. The effects of both variables (private health insurance and years of schooling) are pronounced in the group with good self-rated health but decrease and are not significant among those with poor health status. While the wealthiest have high utilization rates regardless of self-perception of health problems, individuals of low socioeconomic status have to feel ill to seek health care.
In the group with good self-rated health, a possible explanation of the increased use among the richest is the higher use of preventive services. Differences in the main reason for seeking health care among rural and urban populations were evidenced in a previous study in Brazil: while use of preventive services was predominant in urban areas, presence of disease was the main reason in the rural population, which has lower socioeconomic status and more difficulties in the access of health services .
Unequal access to the services provided is another possible explanatory mechanism. Even though universal access to health services is guaranteed by the Brazilian constitution, which has allowed for improvements of many aspects in health [50, 51], some studies have shown inequality in the geographic distribution of available resources, mainly those requiring a more sophisticated technology for diagnosis [52, 53].
The availability, the type and the quantity of services and resources (financial, human, and technological) are aspects of supply that may be influencing the pattern of utilization of health services in Brazil. A study using data from the National Household Sample Survey (2003) evidenced lower utilization by elderly rural residents when compared to old residents of urban areas, even among those who reported health problems. Furthermore, analysis showed that there was limited access to services with intermediate complexity .
An alternative explanation of the pro-rich inequality in health services utilization among those with good health status is that the wealthiest are more likely to use health services excessively, mainly among those that have a private health care plan. Our results show that the odds of outpatient services utilization is 2.7 greater among those with private health insurance than among those without private insurance. As has been pointed out by Starfield and collaborators , the excessive use of health services is becoming increasingly evident and deserves attention, as it is associated with higher costs, more medical procedures and more medications, without producing differences in quality of services . In Brazil, excessive medical interventions during pregnancy and childbirth in the private sector may be influencing the increase in preterm deliveries, diminishing the gains resulting from improved antenatal care and increased newborn survival .
However, neither having private health insurance nor the availability of health services can ensure utilization of health services. Social, cultural and environment aspects are factors that could possibly influence health care use . In Brazil, the lack of knowledge about disease prevention must also be considered, which particularly affects healthy habits, lifestyles and utilization of health care services [59, 60].
On the other hand, the analysis evidenced that the effects of socioeconomic variables on health services utilization are reduced as the level of self-rated health status worsens, or as the health care need is more intense. Furthermore, among those with poor self-rated health, socioeconomic differences in health services utilization were not significant.
So, as compared to previous studies on inequalities in health care utilization [38–43], the present study shows encouraging news. The findings indicate that access and utilization of health services are provided to the population with perceived health problems regardless of educational level and are particularly relevant in the context of reducing socioeconomic health inequalities. Clearly, the evidence depicted here deserves further analysis, taking into account indicators of quality of care received.
Another limitation of this survey is that our measure of health services utilization is based on self-reported data. It is well known that such data are subject to measurement error that arises when respondents are asked to recall past utilization. So, the results here presented should be interpreted in the light of this limitation .