Total hip replacement (THR) and total knee replacement (TKR) are proven interventions for patients with advanced arthritis, and are among the most common elective surgical procedures carried out in the UK and Ireland ¹ . National Joint Registry data for both the UK and Ireland reveals that close to 200,000 total hip and knee replacements are performed each year ^{2, 3} . Demand for both THR and TKR is set to increase dramatically in the coming decades due to changing demographics and an ageing population, with studies suggesting the demand for TKR in the United States will grow by 673% by 2030 ^{4– 6} . Anaesthesia can play a significant role in reducing perioperative morbidity, and in an increasingly complex patient population it is important that patients are given accurate and up to date information about the various anaesthetic techniques used ⁷ .

Internet use is increasing worldwide, with 85% of adults in the United States using the Internet ⁸ . In the UK, the Oxford Internet Survey group stated that in 2013, 78% of people used the Internet and, of these, up to 71% sought health related information ⁹ . Patient education materials (PEM) can be beneficial for assisting patients in the informed consent procedure, by explaining indications, risks, benefits and alternatives ¹⁰ . A recent online poll revealed that up to 90% of patients who access the Internet for their health information believe it to be accurate, and over 60% reported that it impacted their medical decision making ¹¹ . However, the Internet is a completely unregulated source susceptible to provider bias and has the capacity to negatively influence consumer health outcomes ¹² . Implementing and enforcing standards is very difficult, and health information available has been shown to be of poor quality and largely unreliable ^{8, 11, 13, 14} . It is important for doctors to be aware of the information available to patients on the Internet and to understand confusion surrounding such information. As well as supplying high quality accurate health information, the readability of the website must be suitable for the target audience. Several medical organisations , including the National Institute of Health (NIH), and the American Medical Association (AMA) recommend that all PEM should be written at or below sixth grade level (reading age 11-12 years) in order to be effectively understood by the general public ¹⁵ . However many previous studies have shown that a significant proportion of health information websites are written above this recommended level, suggesting that it may be beyond the comprehension of a substantial proportion of the patient population accessing it 16– 18.

Over the past number of years there has been several studies assessing both the quality and readability of PEM available on the Internet across all medical specialties, including general and regional anaesthesia for labour and pain procedures ^{19– 22} . We also already know that orthopaedic patients research their conditions extensively online ^{11, 13, 23, 24} , but to our knowledge none of these studies have looked at the availability of high quality health information relating to anaesthesia for common surgical procedures. Therefore, our aim was to assess the readability and quality of patient information available on the Internet relating to anaesthesia for both TKR and THR.

Out of the 168 initial search results, 32 were analysed further as per the previously described exclusion criteria ( Figure 1). Each website was categorised according to authorship; seven were academic, seven were commercial/physician, five were discussion/social media related, four were physician, four were Government/NPO related, four were commercial and one was media-related ( Figure 2). Only 8/32 sites (25%) were HONcode certified and 5/32 (15.6%) had the Information Standard quality mark.

The DISCERN instrument was used to assess each website. Overall, the mean DISCERN score was low, 40.3 ± 13 out of a maximum of 80. Three of the top five scoring websites were of academic authorship with one being of physician authorship and one Government/NPO. Eight websites (25%) scored 51 or above, representing good quality, with academic authorship associated with both the single highest DISCERN score (61) and the highest mean DISCERN score across all groups (49.7). Six websites (18.75%) scored less than 26 points, representing very poor quality with extensive shortcomings. Average DISCERN scores by authorship groups are shown in Figure 4. Neither HONcode nor the presence of the Information Standard quality mark was associated with a higher mean DISCERN score ( P=0.08 and P=0.7, respectively). Academic and physician-related websites achieved significantly higher mean DISCERN scores than social/discussion networks ( P = 0.005 and P = 0.032, respectively; Figure 5).

There can be no doubt that the Internet has changed the manner in which patients access information. Traditionally, information was passed from doctor to patient in a single direction and decisions were made under the paternalistic guidance of the doctor. In the Internet era, in which information is immediately available, this flow of information is no longer appropriate, nor is it acceptable to patients. More and more, patients are accessing this medical information online and using it to make decisions regarding their own healthcare ^{8, 18} . However, the reliability and suitability of these online patient education materials is increasingly being called into question ^{8, 13, 14, 16– 18} . The majority of Internet users start their search with a search engine, and most do not trawl beyond the websites from the first three pages returned ²² . The aim of this study was to assess both the quality and the readability of Internet information relating to anaesthesia for total hip replacement and total knee replacement, using three validated tools to assess readability (FRE, GFI, FKGL) and the DISCERN instrument to assess quality of information obtained. We also looked for websites that displayed HONcode certification or had received the Information Standard NHS quality mark.

Our results show that 81.2% of the websites assessed were above the recommended sixth-grade readability level for PEM. This should be a concern for healthcare providers; many patients will have a limited understanding of the health information available to them online, and thus even those patient education materials that may be of good quality may not be understood. This could have an adverse effect on the informed consent and decision-making process. These findings echo multiple studies over the last decade, suggesting that producing information at an appropriate readability level is still a challenge for healthcare providers ^{10, 18, 19, 21} . Encouragingly, our study found that websites that had been awarded the Information Standard NHS quality mark were statistically significantly more likely to achieve the appropriate readability level, suggesting that these are the websites that healthcare providers should be recommending to our patients.

The quality of the websites was assessed using the DISCERN instrument. It is important to note that the DISCERN instrument does not take into account the readability of the material, and thus when recommending websites to patients, healthcare providers should seek websites which are of both high quality and appropriate readability. In our study, only a small number of the websites analysed (25%) scored highly using the DISCERN instrument, which indicates that most PEM related to anaesthesia for TKR and THR available on the Internet are of poor quality. Websites were more likely to achieve high DISCERN scores if the authors were physicians, affiliated with academic institutions or government agencies. Again, this highlights the importance of healthcare professionals directing patients towards more reliable and appropriate PEM.

One of the most significant and disappointing findings from our study relates to the presence or absence of the HONcode seal on websites. Although the HONcode seal indicates that a website has met certain quality and reliability standards, our study did not find that HONcode certified websites achieved higher readability or quality standards than those without the HONcode seal. The Information Standard quality mark was introduced to help patients make informed choices about their condition and options for treatment. In our study, we found that although there was a statistically significant relationship between the presence of the Information Standard quality mark and appropriate reading levels, there was no correlation between this quality mark and quality of information using the DISCERN instrument.

A number of limitations to this study are recognised. We performed our online search in one country, and only analysed PEM from websites written in the English language. The search was limited to the first three pages of returned websites, as it has been shown previously that the general public usually don’t pursue beyond this ²² . We acknowledge that comprehension of healthcare information is not solely related to readability of text and that other factors, i.e. videos and visual tools, can contribute greatly to a patient’s understanding. The examination of such materials was beyond the scope of this study and previous studies have also acknowledged this limitation ^{8, 16} . While readability indices have been validated in the literature, there is no general consensus on which index is best and each one uses a different formula to calculate readability. Scores by different indices may vary substantially. It should also be noted that although there is a large volume of material available to guide users when appraising websites using the DISCERN instrument, there is still the potential for variability among raters, which is a limitation not present when assessing readability.

In conclusion, we aimed to assess the quality and readability of information available online regarding anaesthesia for total knee replacement and total hip replacement. Overall, we found that most of the websites were of poor quality and many had reading levels which were too high for the target audience. These findings echo many other studies that examine online information relating to healthcare ^{8, 11, 13, 16, 17, 19, 20} . We found that while the Information Standard NHS quality mark was associated with improved readability, neither the quality mark nor the HONcode were found to have a statistically significant correlation with quality of material. Based on this study we would encourage doctors and other healthcare professionals to be judicious in the websites they recommend to patients, and to consider both the readability and the quality of the information provided.