Stroke is one of the leading causes of disability worldwide, including in Korea, resulting in a significant socioeconomic burden [1,2]. Stroke mortality rates have decreased dramatically with advancements in the emergency medical system and acute care after stroke. However, the stroke incidence rates have decreased less steeply, suggesting that more stroke survivors will live with disabilities [1]. Although early and intensive rehabilitation after stroke is prioritized in many countries [3,4], many stroke survivors eventually experience long-term disabilities, even years after the onset of stroke [5]. A multicenter cohort study in Korea revealed that 38% of stroke survivors had at least one functional dependence, estimated using a functional independence measure 6 months after stroke [6]. During long-term follow-up after stroke in Korea, patients with stroke experience worsening problems in various domains (i.e., communication, cognition, pain, and mood), leading to lower health-related quality of life [7]. Consequently, many patients with stroke have long-term care needs. However, these needs have not been adequately met in several cases. In a recent systematic review of Longer-term Unmet Needs after Stroke (LUNS), approximately 73% of stroke survivors had at least one unmet need [8], which is associated with a low quality of life for stroke survivors or their caregivers [9-11].

Therefore, systematical identification of the current status of unmet needs in various domains using a validated tool is crucial for formulating a policy to adequately and efficiently address unmet needs. A LUNS monitoring tool consists of 22 items for various needs in multiple domains including information, service, social/emotional consequences, and health-related problems of stroke survivors, and it comprises dichotomous (yes/no) responses for each item. LUNS was developed based on previous literature and semi-structured interviews with stroke survivors [12,13]. In an original validation study among 850 British stroke survivors, LUNS showed good acceptability (average completion time of 6 minutes and low missing item rate) [12]. Test-retest reliability analysis revealed high agreement, ranging from 78%–99% for item responses, and a kappa coefficient ranging from 0.45–0.67. Additionally, the validity of the LUNS was corroborated by the identification of unmet needs that consistently correlated with poorer health, as measured by the Short Form 12 (SF-12) questionnaire and Frenchay Activities Index (FAI). However, the LUNS has not been widely translated and validated in languages other than Dutch [14]. The unmet needs of stroke survivors can be influenced by various health and social factors and different coping strategies are required depending on cultural backgrounds. Thus, using the same standardized and validated tool to evaluate unmet needs after stroke in various languages will allow for more inclusion of minority groups in multiethnic countries and enable global comparisons of unmet needs after stroke.

This study had two main objectives: the translation of the 22-item LUNS questionnaire into Korean and the evaluation of its validity among stroke patients in Korea. In addition, we analyzed the reliability between the face-to-face (first test) and telephonic (second test) surveys, to determine the reliability of follow-up telephonic surveys using the LUNS instrument. The successful implementation of this approach provides a valuable opportunity to include a larger cohort of stroke survivors in future research.

In this study, we translated and cross-culturally adapted the LUNS questionnaire to Korean and assessed its validity and test-retest reliability in stroke survivors. Our findings show that the LUNS-K is a reliable and valid instrument for measuring unmet needs in Korean patients with stroke. Field testing is a comprehensive and feasible method. In a larger group, field testing showed high agreement between the face-to-face and telephone tests and yielded a few missing items. For 12 of 22 items, those with unmet needs had significantly lower scores on one or more instruments for activities and quality of life, demonstrating their validity.

In terms of concurrent validity, the results of the original validation study conducted by the LoTS care LUNS study team showed that 21 items were significantly associated with lower scores on the FAI or the SF-12. In our study, however, only 12 items showed significant associations. This difference in concurrent validity findings could be attributed to several factors. First, our study had a smaller sample size, which might have lowered the statistical power and limited the ability to detect significant associations. Second, the higher percentage of unmet needs per item in our study population might have contributed to the reduced number of significant associations. Lastly, the longer timeframe in our study, including stroke survivors at various stages of recovery, could have influenced the concurrent validity results compared to the original study, which focused on participants within the 3–6 months post-stroke period.

In this study, we compared the results of the first survey conducted in person with the second survey conducted via telephone. Of 22 items, 20 showed a moderate reliability or better, while two items (items #7 and #18) showed a marginally fair reliability (κ=0.394 and 0.397, respectively). Considering that the two surveys were conducted using different methods, the reliability of the LUNS-K is believed to be acceptable for clinical usage [22].

The unmet need for aids or adaptation outside only showed marginal reliability between the surveys, with 16.7% of the participants providing a “yes” response to the question. The LUNS-K questionnaire included examples of outside adaptations such as “ramp” or “rail” as in the original LUNS. However, these modifications of the outside environment can be unfamiliar in a Korean setting, as Korean people tend to live in apartments. This lack of familiarity with outside adaptations may have made the question vague for the participants. Thus, a more detailed example or description of the item would increase the reliability of the LUNS-K.

Only 9% of the participants reported that they had an unmet need for “advice on physical relationships.” The very low rate of this unmet need may be associated with its low test-retest reliability (κ<0.4). A previous study including Korean female patients with cervical cancer reported a low response rate for obtaining sexuality-related information [23]. They reported that participants who did not respond to sexuality-related items showed significantly different characteristics from those who responded; they were more likely to be older, unmarried, less educated, unemployed, earning a lower income, and at an advanced stage of the disease. In this study, participants did not avoid responding to sex-related items. However, considering the avoidance of sexual questions among older Koreans, they might have avoided providing an accurate response by expressing no unmet needs. Therefore, we cannot rule out the possibility that they selected “no unmet need” rather than avoid answering because the first survey was conducted face-to-face. Moreover, the question regarding help with voiding/defecation difficulty, which patients may also tend to avoid had a low prevalence (15.2%) but showed substantial reliability (κ=0.709). As such, the causal relationship between low prevalence and low reliability remains unclear. Therefore, the results of sex-related needs in future surveys on unmet needs should be interpreted with caution, due to the older age of stroke survivors and the potential cultural influences affecting their responses.

Identification of unmet needs after stroke is crucial to inform health and social service provision. In addition, understanding the specific needs of stroke survivors is vital for providing patient-centered health and social care. The prevalence of unmet long-term needs is high among survivors of stroke [8]. Patients with stroke who participated in this study most frequently reported a need for information on stroke, followed by concerns about falls, pain, and depression/anger/anxiety. Our findings are corroborated by results from a study on a Dutch stroke population [14] that reported the highest unmet needs in the stroke information domain, suggesting that clinicians should assess the need and provide sufficient information to patients with chronic stroke.

The use of different survey methods is a notable characteristic of the study. We conducted the second survey via telephone, and the response rate was 86.4%. The telephone survey method reportedly has several advantages compared with the postal survey method, including a higher response rate, reduced responder selection bias, and higher retest reliability [24]. Additionally, administering questionnaires via telephone to non-responders of postal surveys resulted in higher response rates (>80%) [25]. Telephone surveys are particularly suitable for stroke patients with physical disabilities and limited mobility. Additionally, with the increasing adoption of social distancing procedures and telecommunication, as seen during the coronavirus disease 2019 pandemic, face-to-face and group meetings have significantly declined. As a result, non-face-to-face survey methods, including telephonic surveys, are now preferred over in-person surveys. Also, conducting in-person interviews requires substantial resources and is impractical for large community populations. Therefore, we anticipate that telephonic surveys will be increasingly employed in future studies.

Our study had a few limitations. First, the inclusion of participants at different stroke stages resulted in various post-stroke periods. Patients with stroke can be classified into different stages, including acute (<3 weeks), subacute (3 weeks–6 months), early chronic (6–18 months), and late chronic (>18 months) [17]. The possibility of changes in unmet needs between the two tests (initical and second surveys) in subacute post-stroke patients could not be excluded. However, the majority of our participants were in the late chronic stage (68.2%), implying that the test was performed in a stable population. Further research should investigate and analyze unmet needs based on the specific stages of chronicity in stroke patients. Second, we did not conduct a test-retest of the face-to-face survey. Instead, the second survey was conducted via telephone. The difference in survey methods may have affected the reliability assessment of the questionnaire, particularly because people tend to respond more easily to sensitive questions via telephone than face-to-face [26,27]. Nonetheless, the advantages of administering telephonic surveys were considerable; the response rate of the second survey was >80%. Moreover, assessing the LUNS-K using both face-to-face and telephone interviews confirmed the validity and reliability of this instrument, as well as its feasibility in clinical settings using different survey methods. Finally, the participants in this study comprised post-stroke patients with the cognitive ability to understand and answer the LUNS-K. This means that the prevalence and validity of the LUNS-K in patients with severe cognitive impairment remains uninvestigated. To address this issue, further studies should include patients with stroke who have severe cognitive impairments by including these patients’ caregivers as needed.

In conclusion, the LUNS-K is a reliable and valid instrument for assessing unmet health needs in Korean patients with stroke. Unmet needs and low health questionnaire values (FAI, MCS, and PCS) were confirmed for 12 items when the validity of the LUNS-K was analyzed. Although the agreement is lower in some parts of the Korean version compared to the original English version, the reliability of the LUNS-K is still acceptable. In addition, this instrument can be reliably applied telephonically as well.