Lost in print: difficulty in reading online information pertaining to phenylketonuria

Abstract

Phenylketonuria (PKU) is the most prevalent inborn error of amino acid metabolism, necessitating patients to strictly restrict dietary phenylalanine. As this can be a confusing and concerning diagnosis, patients and loved ones will likely be drawn to learn more. A critical factor for citizens to harness the health-related digital information is to ensure that it is easy to read. This study assessed the readability of 100 digital articles related to PKU and explored the effect of the source of online information on the readability of these articles. For each article, 5 readability tests were conducted using on-line readability software. From the 100 assessed websites, 34% were commercially sourced. Of the remaining 66 sites, 40% had.org and 17% had.gov extensions. All 5 tests confirm that a large majority of the sample was written at an unacceptable reading level. In fact, over two-thirds of the sample received a readability score within the difficult range for three of the tests, while the remaining two deemed 49% and 45% of the sample as difficult to read, respectively. Commercially sourced websites were deemed to be more difficult to read than the other sites with respect to the two of the five measures. Despite the large amount of PKU information online, most of it may be incomprehensible to the average person and thus miss the mark in helping patients and caregivers manage their condition. Opportunities exist for authors of digital health promotional information to effectively achieve their goal by using comprehensible, easy-to-read language.

Introduction

Phenylketonuria (PKU) is the most prevalent inborn error of amino acid metabolism, with an estimated global prevalence of 1:23,930 live births (Hillert et al. 2020). In PKU, autosomal-recessive inherited variants in the phenylalanine hydroxylase (PAH) gene result in deficiency of the PAH enzyme. PAH is critical to the hepatic and renal hydroxylation of the essential amino acid, phenylalanine into tyrosine (van Spronsen et al. 2021). Complete absence or severely diminished expression of the PAH gene results in hyperphenylalaninemia in the blood and subsequent urinary excretion of phenylketone bodies (Williams et al. 2008). Generally, newborns with PKU seem normal but if untreated, develop symptoms within a few months of birth. Symptoms include neurological problems, microcephaly, brain damage, delayed development and intellectual disability as well as the presence of a musty odor in breath, sweat and urine, due to excessive amounts of phenylketones (Mayo Clinic 2022).

The mainstay of PKU treatment is lifelong dietary restriction of phenylalanine with the goal of maintaining plasma phenylalanine levels within 120–360 umol/L (NORD 2021). Practically, this entails rigorous limitation of dietary protein in conjunction with supplementation of all essential amino acids except phenylalanine (van Spronsen 2010). It is imperative to implement these dietary restrictions early on in infancy and maintain them lifelong, to minimize the extent of intellectual disability (NORD 2021). Women with PKU must adhere to a low-protein diet, with adequate PKU-compatible supplementation before conception and during pregnancy to ensure a healthy pregnancy outcome (NPKUA 2011).

The digital media have become the ubiquitous source of health information and patient education, worldwide. Patients and caregivers pursue online information regarding healthy lifestyle as well as specific concerns such as symptoms, diagnoses, treatment and management of a particular medical condition (Jia et al. 2021). More than 74% of American adults (Finney Rutten et al. 2019), around 55% of European adults (Eurostat 2021), and more than 80% of Asian adults (Wang et al. 2021) seek health information online. In fact, digital literacy has been identified as one of the “super social determinants of health” (Sieck et al. 2021). Recognizing the significance of online information in patient-centered healthcare, the US Department of Health and Human Services’ Healthy People 2020 objectives included increasing the proportion of quality, health-related websites as well as the proportion of online information seekers with easier access to online health information (United States Department of Health and Human Services and Office of Disease Prevention and Health Promotion 2019). Further, the Plain Writing Act of 2010 encourages writing materials in the clearest possible way as well as evaluating them for ease of communication prior to dissemination (Plain Language Act Association International 2010).

A critical factor for citizens to harness the health-related digital information is to ensure that it is readable, especially if the source of information is from health care providers seeking to disseminate science- and evidence-based information for management of a health condition. Digital health literacy is “the ability to seek, find, understand, and appraise health information from electronic sources and apply the knowledge gained to addressing or solving a health problem.” (Norman and Skinner 2006). Digital health literacy thus applies facets of different literacy skills into the realm of digital health promotion. Considering that more than half of American adults read below the equivalent of sixth-grade level (Schmidt 2022), it is imperative that online health information is comprehensible to the average citizen. A prior study analyzing the readability of online PKU-specific information assessed the readability of five PKU-related internet sites (Marsh et al. 2020). Our study builds on these findings by assessing the readability of 100 digital articles related to PKU and classifying them according to the level of difficulty as well as exploring the effect of the source of online information on the readability of these articles.

Methods

The methods for this study were derived from our prior cross-sectional readability study (Ethan et al. 2020; Meleo-Erwin et al. 2019). We used a cleared browser in Google Chrome to perform an Internet search using the keyword “Phenylketonuria” and identify the first 100 websites. Websites were vetted according to the following inclusion criteria: non-sponsored websites or articles in the English language, containing text pertaining to Phenylketonuria as well as the presence of a unique URL prompting to a PKU-related article as opposed to a menu page or “splash.” Websites were also grouped as commercial (.com extension) or non-commercial sources (.org,.gov,.edu extensions) based on the URL. For each article, we recorded the URL, and conducted 5 readability tests using on-line readability software, Readable.io. The 5 readability tests measure the same construct but measures readability is slightly different ways: Coleman-Liau Index (CLI) indicates the reading level of a text by assessing average sentence length and average number of letters per 100 words; Gunning Fog Index (GFI) measures clarity and simplicity by assessing the frequency of polysyllabic words; Simple Measure of Gobbledygook (SMOG) Grade Level estimates the number of years of education needed by an average person to understand a text; Flesch Reading Ease (FRE) analyzes the ease with a text will be understood and engaged with, by calculating the average number of syllables per word and average sentence length and; Flesch Kincaid Grade level (FKGL) estimates the approximate reading grade level of a text by enumerating word and sentence count (Readable.com n.d.).

Readability measures of CLI, GFI, SMOG and FKGL were categorized as “easy,” “average,” and “difficult,” corresponding to below grade 7, between grades 7–10, and above grade 10 reading levels, respectively. FRE scores were categorized based on their scores: 80–100 (easy), 60–79 (average), and 0–59 (difficult). Based on recommended reading levels for health promotion (McKenzie et al. 2017), a minimum FRE score of 80 and scores less than 6.9 on the other assessments were considered acceptable.

All data curation and analysis, which included running descriptive statistics and independent one-tailed t-tests (α = 0.05), were done using Microsoft Excel. Since this study did not involve participation of human subjects, it was not reviewed by the Institutional Review Boards at Lehman College and William Paterson University.

Results

From the 100 assessed websites, 34% were commercially sourced. Of the remaining 66 sites (hereafter called other), 40% had.org and 17% had.gov extensions. Table 1 shows the distribution of readability scores for the sampled websites, first by test and then by difficulty level. All 5 tests attest that a large majority of the sample was written at an unacceptable level. In fact, over two-thirds of the sample received a readability score within the difficult range for the FRE, CLI, and SMOG tests; these articles were written 4–5 grade levels above what is recommended. FKGL and GFI tests deemed 49% and 45% of the sample as difficult to read, respectively. Only one website was rated as acceptable by all five assessments. Mean readability scores and standard deviations of the sampled websites, as well as the averages for.com and other URLs for each of the five readability assessments are shown in Table 2. None of these averages are at the acceptable level.

Table 1.

Distribution of websites by readability assessment^a and difficulty level

Readability scores	Proportion (%) of websites (n = 100
FRE
Easy (80–100)	2
Average (60–79)	21
Difficult (0–59)	77
FKGL
Up to grade 7	16
Grades 7–10	35
Beyond grade 10	49
GFI
Up to grade 7	20
Grades 7–10	35
Beyond grade 10	45
CLI
Up to grade 7	7
Grades 7–10	21
Beyond grade 10	72
SMOG
Up to grade 7	4
Grades 7–10	29
Beyond grade 10	67

^aFRE, Flesch Reading Ease; FKGL, Flesch Kincaid Grade Level; GFI, Gunning Fog Index; CLI, Coleman-Liau Index; SMOG, Simple Measure of Gobbledygook

Table 2.

Mean readability ^a for all sites, top 10 hits, and by URL extension (.com vs. other); p-values for t-tests also included

Readability test	Mean	Standard deviation	Top 10	.com	Other	p-value
FKGL	9.80	2.84	8.86	10.53	9.43	0.034
GFI	9.77	3.90	9.22	10.35	9.47	0.144
CLI	11.39	3.91	11.09	11.95	11.11	0.154
SMOG	11.00	2.65	10.64	11.29	10.85	0.213
FRE	42.66	18.41	48.81	37.05	45.55	0.014

^a FRE, Flesch Reading Ease; FKGL, Flesch Kincaid Grade Level; GFI, Gunning Fog Index; CLI, Coleman-Liau Index; SMOG, Simple Measure of Gobbledygook

Independent one-tailed t-tests (α = 0.05) were conducted to determine if there was a statistically significant difference in the readability scores of commercial URLs vs. non-commercial URLs. The resulting p-values of these tests are given in the last column of Table 2. While no significant difference was detected for the GFI (p = 0.1438), CLI (p = 0.1543), and SMOG (p = 0.2127) scores, there were significant results for the FKGL (p = 0.0335) and FRE (p = 0.0140) assessments. These results indicate that the commercially sourced websites were deemed to be more difficult to read than the other sites with respect to the FRE and FKGL measures.

Discussion

Since phenylalanine is an essential amino acid, medical nutrition therapy for PKU aims to limit phenylalanine consumption at measured amounts that is necessary but tolerable by the patient (Mayo Clinic 2022). PKU-specific medical nutrition therapy entails avoiding high-protein foods such as meats, dairy, nuts, legumes; foods and beverages containing the artificial sweetener, aspartame; limiting tubers, grains and many vegetables; as well as ensuring regular intake of amino acid supplements (NHS UK 2019). Stringent lifelong control of phenylalanine is challenging, and is reported to decline from 10 years of age. Adherence to, and management of a PKU diet regardless of circumstances or social occasion requires proper planning and organization, which can become difficult during periods of greater risk such as puberty, pregnancy and post-partum (MacDonald et al. 2012). Incomprehensible health-related online information can compound the stress related to managing a lifelong disorder such as PKU, for patients, their families and caregivers, in addition to missing the goals for patient-centered healthcare. Since the general population gravitates towards digital media to research options for diet and health as well as the fact that the internet is a practical platform for wide-ranging and cost-effective health interventions (Pollard et al. 2015), it is imperative that the information be presented at a reading level that is comprehensible to the majority of the population. This information can range from seemingly simple practical suggestions for cooking (Macdonald et al. 2020), to the more complex pharmaceutical approaches and research advances such as availability of whey-derived, PKU-compatible glycomacropeptides (Pena et al. 2021; Daly et al. 2022). Our findings that few of the assessed articles were at or below grade 7 reading level alludes that the vast amounts of PKU-related online information may fall short of their intended expectations to educate patients and equip them to manage their condition. Google typically shows 10 search results per page; even the top 10 hits had an unacceptable readability score averaged from all 5 assessments.

Our small sample size, cross-sectional design and restricting the study to websites only in the English language limit generalization of findings. The study did not take into context the goal and target audience of the authoring entity. For example, websites authored by research organizations could be intended for disseminating scholarly information to a research-focused audience rather than a lay person. Despite these limitations, our results allude that despite the large amount of online information available regarding PKU, most of it may be incomprehensible to the average person and thus miss the mark in helping patients and caregivers manage their condition. Opportunities exist for authors of digital health promotional information to effectively achieve their goal by using comprehensible, easy-to-read language.

Author contributions

LS contributed to study conceptualization, study design, data collection; JF contributed to data analysis; CB contributed to study conceptualization and design. All authors contributed to manuscript preparation and review.

Declarations

Ethics approval

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Competing interests

The authors declare no competing interests.