Historically, tuberculosis (TB) has been the leading cause of death globally due to an infectious agent [1]. A total of 1.3 million people died from TB in 2022 (including 167,000 people with HIV), with an estimated 10.6 million people developing TB worldwide, including 5.8 million men, 3.5 million women and 1.3 million children [1]. Furthermore, it is estimated that more than 1 billion people have succumbed to the disease over the past two centuries [2, 3]. With the occurrence of the COVID-19 pandemic, TB was replaced with SARS-CoV-2, as the leading cause of death globally due to an infectious agent, however with the reduction in deaths due to COVID-19, TB has now regained its position as the leading cause of death from an infectious agent [4]. TB predominantly affects several regions around the world, where most cases are seen in Africa (23%), South-East Asia (46%) and the Western Pacific (18%) (World Health Organisation, 2023) [4]. For the year 2021, the World Health Organization listed the following eight countries as high-incidence locations, including; Bangladesh, China, India, Indonesia, Nigeria, Pakistan, Philippines, and South Africa [4] TB is also present in developed Western nations, including UK, Ireland, USA and Australia [4].

Drug-resistant Mycobacterium tuberculosis adds to the global burden of the disease [5]. Multidrug-resistant tuberculosis (MDR-TB) is defined as TB disease that has developed resistance to first-line anti-TB drugs, including isoniazid and rifampicin [5]. Two factors promote drug-resistant TB, extrinsic factors such as social determinants of health in combination with control and prevention services, and intrinsic factors including genetic mutations [6]. Social determinants of health including social, and economic circumstances, impact both TB health and epidemiology. Studies conducted have confirmed that the following factors increase the probability of an individual contracting TB, including living or working in a high-incidence area, low-income, overcrowding, and malnutrition [7–9]. Additionally, inadequate education and access to healthcare results in non-compliance to treatment regimens and thus reduced treatment outcomes [9]. To further support this theory, a study conducted by Mekonnen and Azagew [10] confirmed that non-adherence to anti-tuberculosis treatments, led to the development of increased drug resistance. Consequently, the World Health Organization created the “End TB Strategy” in 2015, aiming to achieve a world free from the TB epidemic, with zero suffering and deaths. The strategy developed, focused on guiding global efforts towards the disease, as well as providing access to care and prevention [11].

Research has shown that limited health literacy has an existing relationship with negative health consequences, including the spread of diseases such as TB and MDR-TB [12]. Individuals need adequate literacy skills in order to understand and navigate healthcare systems, preventing the spread of disease. Education has the potential to improve an individual’s literacy skills, however, individuals learn in various ways and basic literacy skills do not guarantee understanding, particularly within the scientific and medical field [13]. Furthermore, hard-to-reach populations, and populations where drug treatments are used frequently, often have low health literacy levels, thus reinforcing little to no knowledge and awareness with regards to TB onset, diagnosis, and treatment regimens [14].

Establishing the quality of a written piece of text and its level of readability ease is a crucial factor to health literacy [15]. Health education materials frequently ignore individuals’ literacy and comprehension skills, resulting in insignificant information being conveyed. Individuals suffering from TB or MDR-TB, encounter several complex decisions regarding treatment that require an in-depth understanding of the potential risks and benefits involved [16]. For example, patients need to decide whether to complete the lengthy 6-month treatment regime which could potentially result in side effects including loss of appetite, and fatigue [17]. However, factors such as low literacy skills and language barriers, affect this decision-making ability. Patient education resources have the potential to assist in the general public’s understanding and insight into TB and MDR-TB, however such materials must be readable, accessible, and tailored to the target audience. Recently in February 2024, the National Institute for Health and Care Excellence (NICE) published an updated guideline on tuberculosis, which covers preventing, identifying and managing latent and active tuberculosis (TB) in children, young people and adults [18]. In this (1.1.2 Providing information for the public about TB), specific guidance is given regarding the preparation of educational information on TB, which should be tailored to the target population’s needs and be simple and succinct [18].

The hypothesis of the current study is that freely accessible TB information is not presented in a format that is easily readable by the general population, including service users, patients, families, carers and friends. To investigate this hypothesis, the study had the following objectives including, (i) to identify and examine the readability of public/patient-facing TB information (n = 150 sources), (ii) to establish how readable public-facing TB information is compared to UK and US health-literacy readability reference standards and (iii) to compare readability scores across nine different information sources on TB, including (i) the World Health Organization (WHO), (ii) international governments, (iii) hospitals, (iv) non-government organisations (NGOs)/charities, (v) clinical trials, (vi) Cochrane plain language summaries, (vii) matching Cochrane abstracts and (viii) scientific abstracts and (ix) LabTestsOnlineUK.

An overview of the methods employed is shown in Figure 1.

Readability scores for all 150 combined TB information sources, for the Flesch Reading Ease, the Flesch-Kincaid Grade Level, the Gunning Fog score and the SMOG score, are shown in Figure 2. Mean values for the Flesch Reading Ease and Flesch Kincaid Grade Level were 35.6 ± 1.6 (standard error of mean (SEM)) (US Target ≥60; UK Target ≥90) and 12.3 ± 0.3 (US Target ≤8; UK Target ≤6), respectively, with mean words per sentence and syllables per word of 17.2 and 1.8, respectively. Text metrics scores are shown in Figure 2, respectively. Figure 3 shows the Flesch Kincaid Grade Level readability scores for all 150 sources of information, showing the proportion of information sources examined meeting the UK and US targets for this readability parameter. Comparison of FRE and FKGL readability scores for the eight categories of the TB information are shown in Figure 4 and in Tables 2, 3. Comparison of the readability of Cochrane Plain Language Summaries and their matching scientific abstracts are shown in Figure 5.

There was no statistical difference in the Flesch Reading Ease score and the Flesch Kincaid Grade Level, between scientific abstracts (TB) and scientific abstracts (non TB) (Figure 6).

LabTestsOnlineUK yielded a mean FRE score of 51.5 ± 1.2, a mean FKGL score of 10.2 ± 0.5 and text metric scores of 16.7 ± 2.3 and 1.6, for words per sentence and syllables per word, respectively.

Literacy plays an important role in the understanding of tuberculosis [40]. Figure 7 shows the correlation between literacy and the incidence of tuberculosis globally. Whilst this is not a direct cause and effect relationship, it does emphasise the importance of literacy in helping to understand the disease with potential benefits to treatment outcomes and prevention of the spread of infection. Illiteracy is associated with poor adherence and patients’ understanding of the importance of following TB treatment protocols [41]. Therefore, developing resources for TB patients to support treatment literacy of anti-tubculous treatment regimes would be prudent, in order to help patients better understand their antibiotic medications, as well as dosing and treatment durations, in an attempt to maximise treatment adherence.

To our knowledge, the current study is the first to conduct an assessment of the readability of patient-facing, as well as scientific-facing materials which describe multiple aspects of tuberculosis disease, including basic science, epidemiology, symptomology and treatment. In this study, we employed quantitative measurement of words, sentences and syllables, as defined by readability formulae, including Flesch Reading Ease, Flesch Kincaid Grade Level, Gunning Fog and SMOG scores (Table 1), which are commonly described metrics in most readability studies. In the execution of this study, we tried to emulate the journey taken by the patient in trying to find out information on tuberculosis. From examination and comparison of the readability and text metrics results of this study, the overall readability and text metric scores of all combined sources of tuberculosis information did not meet the readability reference targets for either the UK or US.

There is a difference in readability reference targets for the Flesch Reading Ease score and the Flesch Kincaid Grade Level, for US and UK readers, as detailed in Table 4 [16, 42–44]. In the UK, Health Education England (HEE) recommends that patient resources be written at a level suitable for comprehension by an average 11-year-old [16, 42]. In the US, the American Medical Association recommends that all patient-facing material be written at a sixth grade level (11 years old) [44], whilst the US Centers for Disease Control and Prevention (CDC) recommends that patient-facing information is no higher than 8th grade [43, 44].

No information met the UK standard for the Flesch Reading Ease (≥90) and only 2/150 (1.3%) achieved the UK target for the Flesch Kincaid Grade Level (≤6). Twenty three sources of information (23/150; 15.3%) achieved the US reference Flesh Reading Ease score of ≥60 and 20 (20/150; 13.3%) sources reached the US target Flesch Kincaid Grade Level of ≤8. In descending order, TB information from international governments, hospitals and LabTestsOnlineUK were the most readable as defined by the highest mean Flesch Reading Ease scores, of 57.9, 54.1, and 51.5, respectively, whereas scientific abstracts and Cochrane abstracts were the most difficult to read (FRE score = 13.0 and 30.2, respectively). Scientific-facing materials, although not specifically tailored to the general public, are still freely accessible to patients and for this reason, were included within the study analysis. However, as shown in Figure 4, the FKGL and FRE scores for all scientific-facing materials did not meet the required readability targets of either jurisdiction, indicating that the literature would be a difficult read for patients and the public. There was no significant difference between Cochrane Plain Language Summaries and matching Cochrane abstracts, with both having similar difficulty. This finding alone, illustrates that even though plain language summaries are intended to be written in a manner that should be easy to follow and theoretically understandable to the general public, this is not the case.

Clarke and colleagues examined the readability of 17 sources of information relating to the treatment of latent tuberculosis and showed higher readability scores of FKE 63.51 ± 8.81 and FKGL 9.14 ± 8.9, with none of the materials examined meeting HEE recommendations [16]. These authors concluded that current and future LTBI patient education resources would benefit from greater consideration of readability to improve the patient illness experience and support informed treatment decision making. Stossel and colleagues noted that patient education materials are typically written at a college level or higher, making them difficult for the general public to understand and follow [45]. Badarudeen and Sabharwal [43] proposed that by matching the complexity of health education materials to the patients' health literacy levels, it would result in effective communication and perhaps a better understanding of the disease. Similarly, Brennan and colleagues [46] suggested that all patient-facing documents should be prepared and presented to an accessible level in order to meet the needs of the target audience.

Biomedical scientists are important custodians of scientific information relating to tuberculosis for their service user populations, including other healthcare professionals within the TB multidisciplinary (MDT) team, as well as patient service users. Unlike other healthcare professionals, including physiotherapists and dietitians, who have much face-to-face contact with their patient service users, the biomedical scientist’s main mode of communication to this group is through written materials. Examples of these include the description of laboratory tests for tuberculosis, as articulated in the collaborative LabTestsOnlineUK initiative between the Institute of Biomedical Science (IBMS), the Royal College of Pathologists and the Association for Laboratory Medicine (https://labtestsonline.org.uk/). LabTestsOnlineUK has been designed to help the patient to better understand the many clinical laboratory tests that are part of routine care as well as diagnosis and treatment of a broad range of conditions and diseases. The ability to communicate effectively with service users is an important Standard of Proficiency of the biomedical scientist, as detailed by nine descriptors of communication (section 7.1–7.9), as defined by the Health & Care Professions Council (HCPC) [47].

The overall findings of this study conclude that not all freely accessible health information on tuberculosis is delivered in an easily readable format to service users and the general public. In order to meet the basic literacy skills of the general public, readability must be considered by healthcare professionals when producing TB health information and TB patient education materials. Failure to comply with readability standards could possibly lead to health information being misread and therefore potentially misunderstood, potentially resulting in reduced compliance with medical guidance and onwards to poor patient outcomes. To address and combat the increasing incidence rates of TB and MDR-TB, health information should be produced in an easily readable format that service users and the general public find simple and engaging.

This work represents an advance in biomedical science because it shows that TB information from multiple sources has poorly readability. Effective communication of biomedical science concepts and information relating to TB is vital with service users so that they are able to enhance their health literacy of tuberculosis and clinical outcomes.