CONTRIBUTORS
Abdhalah Ziraba
Chief of Staff
Maurine Ng'oda
Research Officer
Background
Longitudinal studies, also known as prospective or follow-up studies, are a type of research design that involves the collection and analysis of data from the same individuals or groups over an extended period at multiple time points. The overarching aim is to understand how their interaction with the natural environment, also known as natural exposure, or an intervention can be linked to an outcome over time. The primary characteristic of longitudinal research is its focus on observing and taking measurements over time from the same individuals. This enables researchers to examine patterns of change, identify factors that contribute to those changes, and explore the long-term effects of certain interactions, also known as exposures, on outcomes. Researchers can also capture the dynamic nature of human behavior and gain insights into biological processes, social trends, and the effects of interventions or policies. Knowing when the exposure or intervention took place enables researchers to establish the temporal ordering of cause and effect, in most cases, which is often an unanswered question in studies that examine associations to infer causality. Examples of longitudinal studies include randomized controlled trials, and cohort studies.
Conducting longitudinal research can be challenging and resource-intensive. It requires long-term commitment and persistence to retain participants, collect data consistently, manage attrition and maintain a healthy relationship with the participants and the community. Additionally, ethical considerations regarding participant privacy, informed consent, changes in research priorities due to changes in funders interests or significant epidemiologic changes that make continued research on a particular issue irrelevant, can all potentially negatively impact longitudinal studies.
Despite these challenges, longitudinal designs provide distinct advantages that are not available in other study designs. These include the ability to determine the sequence of events over time, the researcher’s control in applying interventions through controlled experiments, and the consideration of the time it takes for outcomes to occur after exposure, among other benefits.
In this blog, we discuss the challenges faced by longitudinal studies with reference to a design in which a population in a given geographical area is under continuous health and demographic surveillance over several years.
The use of demographic surveillance systems in longitudinal research
Health and Demographic Surveillance Systems (HDSS), a form of open cohort design, emerged as a powerful tool in generating research data on sub-populations over extended periods in countries with limited civil and vital registration systems. Indeed, several HDSS sites have been established in sub-Saharan Africa, Asia, Caribbean and South America. In Africa, the concept of HDSS is evident in several countries, including Zambia, Senegal, Gambia, Tanzania, Kenya, South Africa, among others. Among other things, HDSS tracks population movements, births, morbidity, and deaths (including causes of death using verbal autopsies) in a defined population over time. It typically operates within a specific geographic area and employs standardized procedures for data collection at predefined intervals. HDSS can be used for evaluating disease control interventions such as immunization program, and as a platform to nest epidemiological studies. Researchers can track individual trajectories, observe patterns of change, and identify critical periods or transitions in life which would not be possible with cross-sectional studies. Since HDSS data collection often occurs at regular intervals, it provides up-to-date information on population dynamics including the ability to monitor health and social trends, track the impact of interventions, and identify emerging issues promptly.
In Kenya, the Nairobi Urban and Health Surveillance System (NUHDSS) has generated data that has shed light on the high burden of ill health, fertility, education, migration and the lack of the much talked about urban health advantage, while in western and coastal Kenya, KEMRI-supported HDSS have contributed to a better understanding of HIV and malaria epidemiology and performance of intervention programs, poverty profiles and uptake of different public health interventions. By their very nature, longitudinal studies and HDSS in particular are riddled with many challenges, including high cost of maintenance, loss to follow up, limited generalizability, changes in research priorities and research fatigue among others. Understanding these challenges helps researchers to pay attention and address them for sound and ethical implementation of research. We focus on the challenge and manifestation of participant research fatigue in a HDSS setting.
Research fatigue
Also known as respondent or participant fatigue, research fatigue refers to the phenomenon where participants in research studies experience decreased motivation, engagement, or willingness to continue their participation over time. This might manifest as loss of interest, avoidance, poor quality responses, negative publicity or outright refusal to participate. There are many causes of participant fatigue and they vary from one study to another. Below are a some of the common causes:
Long interviews/procedures: The length of the interview tool or time-consuming procedures might lead to reduced concentration, interest and potentially errors occurring in the responses. The time spent and the opportunity cost becomes a key issue and motivation for continued participation.
Repetitive data collection: HDSS typically involves regular data collection activities, which may include interviews, or assessments. Participants may experience fatigue due to the repetitive nature of these activities, leading to reduced attention, accuracy, deliberately giving wrong information or refusal to participate altogether.
Poorly designed tools: Complicated and long interview questionnaires may wear out the respondents resulting in participants providing hasty or less thoughtful responses, leading to data quality issues.
Multiple research studies: Participants in HDSS may be involved in multiple research studies simultaneously or consecutively, increasing the likelihood of research fatigue. Engaging in multiple research activities can be overwhelming for participants, leading to reduced willingness or capacity to participate fully in each study.
Lack of community engagement and sensitization: Without proper engagement from inception, the community might not fully understand the purpose and benefits accruing from the research leading to indifference, suspicion and unwillingness to participate. Community consultation during conceptualization and planning creates room for ownership and continued support, which may include but not limited to cascading project information to those who could not attend sensitization sessions.
Breach of confidentiality: In cases where there has been a breach or potential breach of confidentiality is suspected, participants become less willing to provide information of a sensitive nature, for example, on sexual behavior, HIV status, income levels, among others. This is often the case where interviewers are recruited from the same community thereby worsening the concerns on confidentiality.
Poorly trained research staff and unethical behavior: Poorly trained field workers may not be able to explain the objectives of the study, or may engage in unethical misconduct such as not obtaining informed consent properly, not providing correct information or deliberate misrepresentation of facts.
Consequences of participant fatigue
The impact of participant fatigue may vary from minimal signs of disinterest to complete refusal to participate in the study. Reluctance to participate may lead to failure to reach desired sample sizes and hence lack of power to detect associations if they existed. Participants giving wrong responses due to reduced attention or deliberate falsification undermines the research findings’ validity.
Cost escalation is another potential risk as more time might be needed to conduct interviews which could have taken a shorter period were it not for fatigue. Avoidance and refusal to participate might result in selection bias as those who participate might be systematic different from those not participating. In other words, the group of individuals who participate might have certain characteristics, experiences or opinions and reasons for participating that differ from the group that participated. This can skew the results of the study because the sample of participants might not accurately represent the entire population being studied.
Mitigation and lessons from our work:
To mitigate research fatigue, researchers undertaking longitudinal research can implement various strategies to reduce the risk of fatigue. Based on lessons learned from implementing the NUHDSS, the following approaches may work:
- Regular communication with participants on the study aims, providing feedback on study progress, highlighting the importance of their contribution, and offering incentives or recognition for their continued involvement.
- Researchers should also carefully consider the frequency and intensity of data collection activities within the HDSS. Balancing the need for collecting high-quality data with participant burden is essential. Employing efficient data collection methods, integrating data collection, well-trained field interviewers, utilizing technology to streamline the process, and minimizing redundant or repetitive measures can help reduce research fatigue.
Equally important is the need to prioritize participant well-being and ensure their comfort throughout the research process, for example, by using less intrusive tools and procedures. Researchers should monitor and assess participant experiences, providing support or resources when needed to mitigate and monitor potential fatigue or distress.
Studies that do not need a longitudinal framework could be conducted in other areas with no continuous research activity. This might not be easy to implement as the same community might be accessible to multiple research agencies.
Call to action for researchers
Longitudinal research platforms are an immense resource for generating research evidence needed for development. This is critically important in settings with limited resources and a high burden of health and social challenges, which require evidence-informed solutions. However, research fatigue, occurring when participants experience decreased motivation and engagement over time, can affect their success. We need the effort of every researcher to address this challenge and ensure the continued success of important studies.
By staying engaged and participating, research subjects play a vital role in shaping meaningful research outcomes. Regular communication, efficient data collection methods and prioritizing participant wellbeing are some of the strategies we can implement to combat research fatigue.
Your continued involvement can make a significant difference. Join us in the journey to create impactful research that informs development and solutions for pressing health and social challenges. Together we can overcome research fatigue and unlock the potential of longitudinal studies.
Your participation matters!