In Aotearoa, there is long-standing evidence of enduring health inequities related to socioeconomic status and ethnicity. Access to healthcare is a social determinant of heath,[[1]] and differences in the availability and attendance at healthcare appointments contribute to inequitable health outcomes.[[2]] Appointments that are missed or that cannot be attended lead to the later diagnosis and treatment of disease, which worsens disease outcomes, quality of life and mortality rates.[[3,4]] Primary care is a crucial part of the healthcare system and the predominant vehicle in New Zealand by which we treat acute illness, manage chronic conditions, control access to publicly funded secondary services, promote population health and reduce health inequities.

Lack of transportation is consistently cited as a problem to accessing primary healthcare.[[5–7]] In 2019/2020, 6.6% of Māori adults missed general practitioner (GP) appointments due to lack of transport, compared with 2.0% of NZ European adults.[[7]] Māori were 2.9 times more likely than non-Māori to have unmet need on the basis of transport-related access, and Pacific peoples were 2.5 times more likely than non-Pacific peoples.[[7]] Adults in the most deprived areas were 4.1 times more likely to miss an appointment due to lack of transport than those in the least deprived areas,[[7]] and children were slightly less likely across all ethnicities and deprivation indices compared to their adult counterparts.[[7]]

Although rates of car ownership in New Zealand are high, previous studies have shown that up to 30% of New Zealanders do not have access to a car.[[8]] Unequal access to private vehicles among different population groups[[8]] underpins the importance of evaluating access by way of public transport. Public transport helps to address health inequities by providing access to primary care and reducing the environmental impact of transport to healthcare, which contributes to a more sustainable healthcare system.[[9]]

Availability of care tends to be inversely proportional to need.[[10]] Therefore, the location of primary care services in relation to population need could be implicated in some of the reported difficulties accessing care among different groups. A recent study in Christchurch examined accessibility to health and social services by car and on foot.[[11]] The results suggested a rural–urban gradient, with poorer availability of services further away from the central city (although one notable exception was the more deprived eastern suburbs, which had poorer access relative to centrality, which is suggestive of social inequity in accessibility). Previous studies in Auckland have found that public transport provision prioritises higher income areas and services are not of sufficient frequency to meet need. These studies also noted a significant opportunity to enhance spatial access to healthcare by increasing public transport provision in areas of high need. [[12–14]]

The aim of this study is to undertake a spatial analysis of access to primary healthcare for patients using public transport in Ōtautahi Christchurch, and to examine whether accessibility varies across neighbourhoods, populations and indices of deprivation.

Methods

The study area was defined by the extent of the public transport (bus and ferry) network serving the city of Christchurch and surrounding areas (Figure 1), including Rangiora to the north, Rolleston and Lincoln to the south, hereafter referred to as “Greater Ōtautahi.” The public transport system is predominantly bus based, with one ferry service.

Figure 1: Extent of Greater Ōtautahi study area.

We undertook a spatial analysis of public transport accessibility to primary care (specifically general practices) within Greater Ōtautahi and explored the relationship with population demographic data.

General practitioner (GP) locations were provided by the Ministry of Health (MoH) based on Healthpoint data. Public transport stops and timetable data were obtained through the Google Transit Feed Specification (GTFS)[[15]] for the week of 9 November 2020. OpenStreetMap road network data were used.[[16]] Population data were sourced from the 2018 census[[17]] and NZDep2018.[[18]]

To establish the need for the public transport network in providing access, we used the road network distance, as opposed to Euclidean distance used in previous studies, to undertake preliminary analysis and ascertain the population living within 400m and 800m of a GP or medical centre.[[1,11]] An 800m walking buffer has previously been used as an upper limit for accessing primary care on foot.[[19]]

For the main analysis, we report three measures of access: time taken to reach the nearest service; the number of options within a given time threshold; and frequency of public transport services. All results are disaggregated by population age, ethnicity, deprivation and household car ownership.

Time taken to travel to the nearest service

Network Analyst and the Transit Feed toolset in ArcGIS Pro were used to calculate services areas around GP locations. Given the focus on access provided by the public transport system, we clipped the road network to allow a maximum of 400m (five minutes at 4.5km/hr) walk at either end of the public transport journey. These metrics were informed by evidence that people will walk up to 400m to public transport stops or stations,[[20]] a value typically used by urban planners. An upper limit of 800m has been suggested, with an inverse relationship between required walking distance and public transport use becoming marked beyond the 800m walking threshold.[[20]] We constructed service areas showing the population able to access a GP within 10, 15, 20 and 30 minutes by walking and public transport. Service areas were overlaid with sociodemographic data at Statistical Area 1 (SA1) level using proportional overlap.

The number of options available to people within a specified time threshold

People often choose to attend a GP other than the nearest available.[[21]] To account for the number of options available to the population, we calculated the number of GPs within each time threshold from the meshblock centroids (centre-points of statistical area units). Results are reported according to the meshblock deprivation level.

Frequency analyses

In addition to measures of time taken to travel, public transport frequency is also an important measure.[[14]] Stops with frequent services are generally considered to be those with four or more trips per hour.[[22]] We isolated stops with a minimum of four departures per hour and created 400m buffers around them to identify the proportion of the population living within range of a high frequency service. Service areas were overlaid with sociodemographic data at SA1 level using proportional overlap.

Results

Preliminary analysis showed that 14% of the total population of Greater Ōtautahi lived within 400m (approximately a five-minute walking time) and 41% within 800m (a 10-minute walking time) of a GP (Figure 2). Given that the majority of the population do not live within a reasonable walking distance of a GP, the importance of considering access by public transport is clear.

Figure 2: 400m and 800m walking buffers around medical practices.

Time to nearest GP by public transport

Figure 3 and Figure 4 show the areas of the city that fall within each of the journey time thresholds (service area polygons). For example, areas shown in light blue are within 10 minutes of the nearest GP by public transport, whereas those areas not coloured are more than 30 minutes of the nearest GP by public transport. Table 1 shows the proportion of the population that falls within each of these service areas. Overall, 39% of the population are within 10 minutes of their nearest GP by public transport and 28% of the population cannot access a GP within 30 minutes using public transport.

Table 1 shows that, across the city as a whole, the least deprived areas and NZ Europeans have poorest levels of access in terms of journey time to the nearest GP. Households without a motor vehicle (56%) are more likely to live within ten minutes of their nearest GP than households with a car (39%). Children (ages 5–14) have poorer access than those in older age groups across all time thresholds. The 65+ group has access comparable to that of the general population. Young adults (ages 15–29) consistently have the best access. Despite the overall pattern of poorer access in more peripheral areas, Figure 3 shows that there are some relatively central areas with poor levels of access to GPs, particularly in the eastern suburbs.

Figure 3: Areas of Greater Ōtautahi that can access a GP within 10, 15, 20 and 30 minutes using public transport (city focus).

Figure 4: Areas of Greater Ōtautahi that can access a GP within 10, 15, 20 and 30 minutes using public transport (full study area extent).

Number of GP options available

Figure 5 shows the proportion of the meshblocks within each deprivation decile that has different numbers of GPs available within 15 minutes. For example, 31% of the meshblocks in decile 6 have more than four general practices accessible within 15 minutes using public transport. Across the population, 30% of meshblocks cannot access a GP using public transport within 15 minutes. When considering those with the most (4+) options, it can be seen that more deprived areas (NZDep2018 decile 6 and greater) are more likely to have four or more options accessible within 15 minutes. When looking at longer journey time thresholds (Appendix), the majority of meshblocks in all deciles (except the least deprived) have access to 4+ GPs within 30 minutes by public transport.

Figure 5: Proportion of meshblocks that have 1, 2, 3 or 4+ medical practices within 15 minutes using public transport, by NZDep2018 X[[2]] (36, N=4,923)=733.48, p=<0.01.

Frequency analysis

Overall, 41% of the meshblock centroids were within 400m of a high-frequency bus stop (at least four departures per hour). This varied based on deprivation, with 18% of centroids in the least deprived (decile 1) areas compared with 58% of centroids in the most deprived areas being within 400m of a high-frequency bus stop (Table 1). Of the major ethnic groups, Asian had the highest proportion of people (52%) within 400m of a high-frequency route, followed by Pasifika (47%), other (43%), Māori (42%) and European (38%). Similar to the journey time metric above, 15–29-year-olds had the best access from a service-frequency perspective, with 46% living within 400m of a higher-frequency route. Children aged 5–14 had the poorest access to a high-frequency roue at 37%. Households without a vehicle (57%) were more likely to live in proximity to a high-frequency route than those with a vehicle (40%) (Table 1).

Table 1: Population (%) with access to (a) a GP within journey time thresholds by public transport and (b) a high-frequency bus stop, by demographic group and deprivation. View Table 1.

Discussion

This project aimed to explore public transport access to primary care in Greater Ōtautahi and fill a significant knowledge gap related to primary healthcare access in New Zealand’s second-largest city. Across all three metrics of accessibility (journey time to nearest GP; number of GPs within different time thresholds; proximity to frequent public transport services), we found poor levels of accessibility across the study area, which is problematic from a health equity and sustainability perspective. Despite overall poor access, results indicate that public transport provision is greatest in more deprived areas, which is consistent with previous international research.[[1,23,24]]

Overall, public transport accessibility to primary healthcare across the city is poor, with almost 30% of the population in Greater Ōtautahi being more than 30 minutes from their nearest GP by public transport. In comparison, 99.5% of England’s urban population can reach a GP within 30 minutes by public transport.[[25]] Although 58% of the Greater Ōtautahi population can access a GP within 15 minutes using public transport, this compares to 79% of the urban population of England.[[25]] Research elsewhere has also reported considerably greater levels of access to GPs by walking in urban areas than we found here.[[1]] Previous research suggests that 99% of the population of Greater Ōtautahi can reach a GP within 10 minutes of driving,[[11]] whereas we found that only 41% can reach a GP within 10 minutes of walking, and that 39% can use public transport to reach a GP within 10 minutes. This discrepancy in the level of accessibility to primary care between different modes of transport is problematic from an equity perspective, given patterns of car ownership and access across the population, and from a sustainability perspective, given that reducing levels of car dependence requires adequate accessibility by other modes. Those in more deprived areas are more likely to have a greater number of options of GP practices accessible by public transport (Figure 5).

The overall frequency of services was low, which is particularly problematic for those living in the most deprived deciles who might be more likely to rely on public transport due to lower rates of household car ownership. In the most deprived areas, 42% of the population are more than 400m from a high-frequency service, and 56% of households own one or no vehicles to serve an average household size of 3.7 (2018 census).

At a city level, levels of accessibility to primary care reflect the social geography of the city, in that those living in more peripheral, affluent peri-urban areas have the poorest levels of access, which is consistent with previous research.[[1,23,24]] However, even in more central areas there are levels of poorer accessibility for particular groups, particularly in the eastern suburbs (Figure 3), as previously identified.[[11]] There are comparatively poor levels of access for children (aged <15). The 65+ group, who have a greater dependence on public transport[[13]] and who often have higher health needs, had access levels comparable with those of the general population (Table 1).

It is not straightforward to assume that these city-level patterns mean that there are no problems of access among disadvantaged populations. Poorer public transport access in peri-urban areas may be less likely to translate to unmet need given the high socioeconomic status of populations in these areas and high levels of household car ownership. It is therefore important to consider accessibility relative to need. Data are not currently available on the usage of public transport to access healthcare, but future studies should seek to understand the extent to which populations use public transport to access healthcare and how that relates to availability of services. Studies such as ours, which consider potential accessibility to healthcare based on time/distance separation of people from facilities, are common and important in understanding the distribution of resources at the population level. However, despite known inequities in realised access, or utilisation, and health outcomes, we do not find corresponding inequities in provision of transport to primary care. This suggests that other approaches are also needed.

A pro-equity policy approach would improve the situation of the most disadvantaged first.[[26]] Future studies of access to healthcare might be to focus on transport accessibility among populations with known health and utilisation inequities. Future studies could consider setting minimum levels of access relative to need and urbanity, with recognition that closer proximity to services can be expected in denser urban areas and that improving provision of primary healthcare in more deprived urban areas can reduce health inequities.[[1,27]]

Objective measures of spatial accessibility make assumptions about the ability of individuals in terms of mobility and the appropriateness or affordability of both public transport and healthcare services. However, older people may experience reduced mobility, meaning their journey times are typically longer than what is modelled, large families may not be able to afford public transport services and some people may experience racism and safety concerns on public transport. Consideration needs to be given to non-spatial barriers to accessing care, such as affordability, acceptability and appropriateness of services, recognising that the nearest facilities may not actually be considered accessible from the patient perspective. Furthermore, we have not considered the capacity of practices relative to population, which is important given variation in the size and resources available at different practices. As we noted in the results, the relatively poor access to GPs in some central areas suggests a need for further research into the density of primary care services relative to population need.

Although measures of access to the nearest service are typically used, they do not reflect the usage of primary care in New Zealand. In a study using patient registration data in the Waikato it was found that almost 70% of people bypassed their nearest service.[[21]] A number of service factors were identified as explanations for this bypassing of the nearest service, such as hours, clinic fees, after hours and provision of Māori health services.[[21]] It is therefore important to consider the number of different options available to the population, especially where the nearest service is bypassed for reasons of availability of appointments, cost or Māori health services. Indeed, the Waikato study found that non-European ethnic groups were most likely to bypass the nearest service, implicative of the need for not only spatial proximity, but availability of culturally appropriate and acceptable services.[[21]] Although we did not explicitly consider the services provided at different GP locations, we considered the number of options available as a proxy for this.

Understanding levels of non-car access across the population is important from a sustainable transport and healthcare system perspective. A high level of car dependence in New Zealand has negative effects on individual, population and environmental health[[28]] through reduced physical activity and increases in associated chronic illnesses, air and noise pollution, climate change, road safety, social isolation and exclusion from accessing essential services such as employment, education and healthcare for those without a car. The results of this study suggest that the levels of access to primary care through walking or public transport are not sufficient for a major urban area, potentially leading to forced car ownership[[29]] and reducing disposable income for other necessities, including healthcare. As the transport and health systems shift towards meeting environmental sustainability objectives, it is vital to understand how the existing systems can support reduced car dependence without widening existing inequities in accessing healthcare. Our findings suggest that this requires consideration of the existing public transport provision and the locations of GP services across the city. Strategic planning of the location of primary healthcare services relative to population need to improve access could help address equity and sustainability issues in the health system and should be considered as part the current health system reforms

Conclusion

The findings of this study emphasise the need to prioritise the most vulnerable groups when planning improvement in the connectivity between people, the public transport system and primary healthcare. Despite pervasive issues of inequity in health outcomes and utilisation of healthcare services, there is limited evidence of disparities in accessibility when considered at a city level. However, more consideration needs to be given to the level of access relative to need. There is the potential to improve access for disadvantaged groups, and thus improve health outcomes and address health inequities. Improving public transport accessibility can also help to meet health system sustainability objectives.