The articles assessed cover global studies stretching from Asia, Europe, and Africa. A total of 50 studies were screened, 47 articles that did not meet the inclusion criteria were removed, and only 7 articles that met the inclusion criteria were considered as shown in Table 1. All articles included were in line with PHC services for older persons with NCDs or chronic diseases.

The narrative review found that effective PHC services influence better health outcomes. However, the study by Zaidun et al ²⁰²⁴14, which assessed the impact of PHC services intervention on the quality of life of elderly persons in March 2024, was vague as it only concentrated on PHC interventions, leaving out the component of PHC services. In another study 15, it was observed that an independent and positive association exists between the PHC score and the mental component of HRQoL, and an inverse association with the physical domain was observed. This study focused on the PHC score without considering the specific health conditions of the elderly, despite being conducted among elderly persons with chronic diseases. The findings revealed an independent and positive association between the PHC score and the mental component of quality of life, while an inverse association was noted with the physical component 15.

A systematic review study by Santos et al (2013) on the impact of PHC interventions on older persons found the HRQoL of older persons accessing PHC services in low- and middle-income countries to be poor, and that a weak PHC system exposes older persons to poor health and increased mortality 15. The same systematic review study by Santos et al (2013) found that the WHQoL and HRQoL tools were the most commonly used for measuring HRQoL. However, none of the studies reviewed utilized the CDC, HRQoL-14 tool to assess the HRQoL of older persons with NCDs, despite its prominence and effectiveness in measuring both physical and mental health outcomes in older populations.

Concerning PHC services access, studies by Aguiar & Da Silva (2022) and Effendy et al (2022) indicate that PHC services access plays a great role in enhancing improvements in health outcomes 16, 17. Limited access to PHC services negatively impacts HRQoL 16, and Effendy et al.'s study shows that 61.3% of older individuals with NCDs have unmet palliative care needs, with over 60% of hospitalized patients requiring palliative care that is often overlooked by clinicians 17. This neglect leads to delays in early treatment and management interventions. The same research highlights a lack of clinician awareness regarding the palliative care needs of patients living with NCDs 17. Additionally, delayed identification of palliative care needs negatively impacts the HRQoL of the patients and leads to death. Relatedly, Haque et al.'s study indicates that there is an unmet need for palliative care services by patients with NCDs, mostly in LMICs, due to poor budget allocation for healthcare, inadequate training of health providers, and poor access to primary healthcare facilities 18. WHO conducted a scoping review on rehabilitation and PHC using the PubMed database between 2008 and 2018, and reported that 64% of the studies mentioned rehabilitative care referral by primary healthcare workers as a challenge 19. The Global NCD plan (2013-2020) recognized rehabilitation as a vital and key health strategy to address NCD risk factors as well as loss of function due to the health effects of NCDs 1. About 2.5 million people globally have conditions that need rehabilitation care, and NCDs are one of the conditions that predispose people to rehabilitation 1. The same report highlights that in 2020, about 50% of the disability-adjusted life years were due to NCDs, specifically in low-income and middle-income countries.

The narrative review found effective PHC services to be linked to HRQoL. However, the HRQoL of older persons accessing PHC services in low- and middle-income countries was sub-optimal. Similar findings were observed 2021, where effective PHC services in both developed and developing countries were found to be associated with enhanced healthcare services and better health outcomes 22. Inadequate access to healthcare services, although previously more common in high-middle -income countries, is now increasingly affecting LMICs 21. The literature underscores the need for a collaborative approach in PHC services to enhance community access to appropriate healthcare. Along these lines, 23 posits that effective delivery of PHC services can lead to improvement in the HRQoL. However, the primary healthcare system is currently unprepared to manage the increasing burden of NCDs, as highlighted by other research findings 24. Further, a closely related study 25 observed that an independent association between PHC score and the mental health component of HRQoL exists, and an inverse association with the physical component was observed. However, the study 26 centered on comparing tools for measuring the physical and mental outcomes of the patients that influence their HRQoL.

An analysis of the effectiveness of the PHC system shows that a weak PHC system exposes older persons to poor health and increased mortality 14. Conversely, other closely related studies found that effective PHC services resulted in desirable outcomes, with improvements across all domains of HRQoL 272829. Despite improvements in HRQoL in the previous studies, Woo s study revealed an interesting aspect: many older persons were not sure if they were taking their medications correctly 29, which raises patient safety issues that require urgent attention. A study done in India found that preparedness for comprehensive PHC care, including prevention, diagnostic interventions, treatment, and rehabilitative care for NCD patients, is sub-optimal due to critical gaps in the healthcare setting 30. This finding aligns with Baum's research, which found that a comprehensive PHC approach encompassing a wide range of health services and activities—from preventive, curative, promotional, and rehabilitative care—positively influences community health outcomes 31.

Specifically, Baum reported that effective PHC services enhance the rehabilitation of patients who suffer complications from NCDs, hence promoting HRQoL 31. Similarly, the study "Strengthening Primary Healthcare Services to Help Prevent and Control Long-term ^Chronic NCDs" confirms that a comprehensive primary healthcare strategy has been identified as an effective approach for reducing health inequities and improving community well-being 21. It emphasizes that the prevention of NCDs is possible through a primary healthcare approach, but only with strong intersectoral collaboration. This approach also enhances community access to appropriate healthcare, promoting health equity and improving HRQoL 21.

The major challenge with PHC services is identifying individuals with palliative care needs and the actual provision of palliative care itself 19. The WHO report reinforces this point, showing that 64% of the studies, including their scoping review, indicated challenges in rehabilitative care referrals by clinicians or primary healthcare workers 19. Another study revealed a discrepancy in findings, showing that despite a lack of trained workforce and adequate funds, physicians in Myanmar still provide palliative care to patients despite these challenges 32. Overall, the effectiveness of PHC services in countries like India and Sri Lanka can be attributed to better healthcare service provision and equitable access to healthcare compared to other developing countries where access to PHC services is suboptimal.

This study was a narrative literature review which has some limitations. Unlike systematic reviews, narrative reviews are more susceptible to reporting bias. However, the narrative review approach was chosen for its ability to provide comprehensive, evidence-based insights into PHC services and HRQoL, and has the potential to aid in the development of theoretical frameworks. To mitigate bias, a structured review process protocol was followed, and careful attention was given to the quality of the included articles.