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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Corresponding author.
$ l.bacco@unicampus.it (L. Bacco); felice.dellorletta@ilc.cnr.it (F. Dell'Orletta); m.merone@unicampus.it
(M. Merone)</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Natural Language Processing in Healthcare: A Bird's Eye View</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Luca Bacco</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Felice Dell'Orletta</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Mario Merone</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Engineering, Unit of Computer Systems and Bioinformatics, Campus Bio-Medico University of Rome</institution>
          ,
          <addr-line>Via Alvaro del Portillo, 21, 00128, Rome</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>ItaliaNLP Lab, National Research Council, Istituto di Linguistica Computazionale “Antonio Zampolli”</institution>
          ,
          <addr-line>Via Giuseppe Moruzzi, 1, 56124, Pisa</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2023</year>
      </pub-date>
      <volume>000</volume>
      <fpage>0</fpage>
      <lpage>0001</lpage>
      <abstract>
        <p>The healthcare industry is experiencing an unprecedented era of transformation, driven by the proliferation of Electronic Health Records (EHRs) and the emergence of vast amounts of natural language data from sources like social media. This dynamic landscape presents novel opportunities for companies, healthcare practitioners, and researchers, underpinned by the transformative potential of Natural Language Processing (NLP) technologies. This paper ofers a brief overview of the rationale for studying NLP in healthcare, highlighting its foundational importance. It explores the current trends and invaluable resources available in the field, while also delving into the multifaceted challenges that must be addressed to harness the full potential of NLP in healthcare. By consolidating essential insights and bridging the gap between opportunities and challenges, this manuscript serves as a valuable resource for both established researchers and newcomers seeking to navigate the complex terrain of NLP in healthcare, ultimately contributing to the advancement of this critical domain.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Natural Language Processing</kwd>
        <kwd>Healthcare</kwd>
        <kwd>Review</kwd>
        <kwd>Electronic Health Records</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        When we mention Artificial Intelligence (AI) in healthcare, we often imagine systems adept at
interpreting sensor data — such as time series from physiological measurements and medical
images — to provide invaluable diagnostic support to healthcare professionals and patients alike.
However, a substantial portion of patient information moves through the healthcare ecosystem
in the form of natural language narratives [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. These textual data hold immense potential (and
need) for automated processing and analysis.
      </p>
      <p>The past few decades have witnessed a profound digital transformation across industries,
including healthcare. This transformation has unleashed a torrent of data from diverse sources
alongside new opportunities and challenges. The opportunities ofered by Natural Language
Processing (NLP) in healthcare are vast and intricate, rendering a comprehensive review
impractical. For newcomers venturing into this field, navigating this complex landscape can be
overwhelming.</p>
      <p>
        In recent years, several researchers have undertaken the task of dissecting this field from
various angles. Some have focused on the learning techniques employed in the literature,
such as machine and deep learning [
        <xref ref-type="bibr" rid="ref3 ref4">3, 4</xref>
        ]. Others have focused on specific data sources, either
electronic health records from healthcare institutions or unstructured data from social media
platforms [
        <xref ref-type="bibr" rid="ref5 ref6 ref7">5, 6, 7</xref>
        ]. Among those works, Gao et al. [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] have compiled a valuable resource
by cataloging publicly available datasets in clinical NLP, which researchers are exploiting to
overcome privacy concerns (see Section 4). Nonetheless, most of these investigations have
revolved around specialized subdomains within healthcare and clinical practices, such as mental
health [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ], orthopedics [10], and dentistry [11].
      </p>
      <p>Thus, this paper aims to provide a concise overview of the panorama of NLP in healthcare,
ofering condensed insights into data sources, tools, current trends, and persistent challenges,
providing a guiding beacon, especially for NLP researchers and practitioners embarking on the
healthcare field.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Data sources</title>
      <p>
        Electronic Health Records (EHRs) The healthcare industry is in the midst of a rapid digital
transformation, marked by the widespread adoption of Electronic Health Records (EHRs), also
known as Electronic Medical Records (EMRs), in hospitals and clinics worldwide [12, 13]. These
clinical documents often contain approximately 80% of unstructured data [14], primarily as free
text. In clinical practice, healthcare professionals exchange patient information as narrative
notes and reports [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
      </p>
      <p>Besides ofering a more comprehensive description of a patient’s health status compared to
quantitative data alone, these natural language reports can be time-consuming to understand
and redact. Not surprisingly, the development of NLP in the healthcare sector has paralleled
the increasing adoption of EHRs. NLP tools have emerged as essential solutions for eficiently
managing unstructured data within these records. Automatically analyzing patients’ records
not only facilitates access to a wealth of information but also serves the needs of physicians,
healthcare companies, patients, and researchers.</p>
      <p>
        The World Wide Web (WWW) In addition to EHRs, the proliferation of the World Wide
Web (WWW) has opened up new opportunities for the NLP community to harness data from
sources like forums and social media to enhance healthcare services [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. Given the vast volume
of text-based information exchanged daily on the WWW, this digital landscape presents an
unprecedented opportunity for NLP researchers and practitioners. It serves as an invaluable
source of textual data for training NLP systems, often through web scraping technologies [15].
Beyond general-purpose social media platforms, the WWW has spawned specialized online
health communities such as PatientsLikeMe1 and DailyStrength2. These platforms bring together
users with similar health-related interests and concerns. Other platforms on the Internet consist
1https://www.patientslikeme.com/
2https://www.dailystrength.org/
of websites for spreading medical information. NLP researchers are already making use of
resources like Wikipedia and SimpleWikipedia3, and the MSD Manuals4 [16].
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Tasks</title>
      <p>Within the vast panorama of NLP applied to healthcare, various tasks exist, each ofering benefits
to multiple stakeholders. Although the division proposed here is not an absolute categorization
(i.e., some of the solutions may benefit more stakeholders), it serves as a handy framework for
understanding the diverse applications of NLP in this domain.</p>
      <p>
        Tasks for physicians NLP tasks designed for physicians predominantly revolve around the
generation/extraction of critical information from EHRs. These tasks serve as tools for lightening
the workload of healthcare professionals and enhancing decision support for physicians [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. For
instance, the development of Natural Language Generation (NLG) systems proves invaluable in
creating clinically precise structured reports from various clinical documents or condensing the
extensive notes generated daily throughout the care process [17]. Conversely, Natural Language
Understanding (NLU) systems function as Information Extraction tools, directly harvesting
pertinent data from these reports, encompassing diagnoses, medication records, treatment plans,
and other essential entities. Through these functionalities, NLP systems show the potential
to empower clinicians with evidence-based recommendations and timely alerts, elevating the
caliber of medical decision-making. Simultaneously, they alleviate the burdens associated with
manual data entry, enhancing eficiency and accuracy in healthcare practice.
      </p>
      <p>Tasks for institutions Automated analysis of text data within EHRs holds tremendous
significance in enhancing the management of healthcare services provided by organizations. For
instance, healthcare institutions can harness NLP to predict the risk of patients’ readmissions.
This predictive capability facilitates the implementation of targeted interventions, optimizes
resource allocation, reduces hospital readmission rates, and ultimately lowers costs [18].</p>
      <p>Another valuable application of text analysis in EHRs involves streamlining administrative
tasks for healthcare facilities. It is achieved by automating the coding activities involved in
billing processes. Diagnoses and procedures are usually encoded using standardized
nomenclatures such as the International Classification of Diseases (ICD), overseen by the World Health
Organization (WHO). These codes simplify health data comparison across populations and
support epidemiological analyses. Currently, the responsibility for this classification process
often falls on trained or even untrained personnel within healthcare institutions. Given the
task complexity and time-intensive nature, it poses challenges even for professionally trained
staf and is prone to errors. These errors can result in financial losses and potential legal
consequences. Consequently, there is a growing interest in developing automatic systems for ICD
coding, as evidenced by various research eforts [ 19] focused on clinical note extraction, such
as discharge summaries.
3https://en.wikipedia.org/wiki/Main_Page, https://simple.wikipedia.org/wiki/Main_Page
4https://www.msdmanuals.com/</p>
      <p>Beyond EHRs, the World Wide Web (WWW) is a crucial resource for healthcare institutions.
NLP-driven surveillance systems can actively monitor digital sources, enabling the early
detection of disease outbreaks, emerging trends, and even signs of suicidal intentions [20, 21],
allowing timely and proactive responses.</p>
      <p>Moreover, just as consumers seek product or service reviews before making decisions, patients
actively seek and share health-related experiences online [22, 23]. Healthcare companies
can derive significant benefits from automating the analysis of patients’ opinions to identify
strengths and weaknesses in their services and treatments.Automated tools ofer the advantage
of processing a vast number of reviews, eliminating the need for traditional structured surveys
and questionnaires that limit patient expressiveness and are costly and time-consuming to design
and analyze. This type of analysis is commonly known as sentiment analysis or opinion mining,
a task that has garnered extensive attention in various domains within the NLP community, yet
remains relatively underexplored in healthcare [24].</p>
      <p>Tasks for patients The World Wide Web (WWW) empowers patients to access a wealth
of information, one of the Internet’s foremost virtues being its democratic provision of easy
access to vast knowledge resources. However, the abundance of medical information available
online can pose challenges for patients without medical backgrounds, who may misinterpret
these resources [25], potentially leading to harmful consequences. In this context, NLP is
emerging as a valuable tool for simplifying health-related texts, bridging the expertise gap for
patients [16, 26]. However, the Internet, particularly on social media and similar platforms, can
be disseminated with medical misinformation. Consequently, several researchers have recently
dedicated their eforts to detecting health-related fake news and combatting what has been
termed the infodemic [27, 28].</p>
      <p>Another popular application benefiting patients is chatbots, digital agents designed for
interactive conversations with users. These chatbots ofer a friendly and engaging means of
educating patients to enhance adherence to care treatments and provide real-time support for
their decision-making skills. Notably, studies have shown that patient education becomes more
efective with increasing interactions with care providers number [ 29]. In this context, chatbots
hold significant promise for helping patients cultivate healthier habits at scale, ultimately
reducing hospital admissions, healthcare costs, and time commitments. Within this framework,
NLP solutions have already begun to play a pivotal role as healthbots: Parmar et al.[30] conducted
a review of healthbots available on the major mobile app stores. However, their findings revealed
that most healthbots rely on rule-based approaches and finite-state dialogue management,
leaving space for the latest advancements in NLP for application in healthcare.
Tasks for biomedical researchers NLP represents an unprecedented opportunity for
biomedical researchers. Apart from employing NLP to extract and summarize information
from vast biomedical literature databases, researchers can exploit its techniques to ease the
recruitment of patients for studies by identifying people meeting the study criteria from the
clinical notes [31, 32], perhaps with appropriate adjustments to handle variations in clinical
documentation between diferent institutions [ 33]. This expedient leads to building larger
cohorts with fewer eforts, which is extremely useful for researchers in the biomedical field.
Furthermore, NLP can be employed to annotate patients’ health status from their reports,
providing silver labels to associate with other kinds of data, like images, and then train the principal
AI system, which is often data-hungry, in a supervised way [10].</p>
    </sec>
    <sec id="sec-4">
      <title>4. Challenges</title>
      <p>The integration of NLP in healthcare has encountered and continues to face unique challenges.
The main concern is the imperative to safeguard patient privacy, given that narrative reports
within healthcare are filled with sensitive information governed by stringent legislation, such
as the U.S. Health Insurance Portability and Accountability Act (HIPAA) and the European
Union’s General Data Protection Regulation (GDPR). The implications of these regulations
are profound, demanding the implementation of appropriate measures to protect individuals’
privacy. However, the costs and reliability challenges associated with de-identifying health
reports present a prominent hurdle for the NLP community in healthcare. These issues constrain
access to shared data, inhibiting collaboration and reproducibility among researchers’ teams [34].
Not surprisingly, the first shared task for clinical NLP in 2006, the Integrating Biology and the
Bedside (i2b2), was centered on the automated removal of Private Health Information (PHI)
from medical discharge records [35].</p>
      <p>To handle this issue, many researchers have focused their eforts on publicly accessible clinical
note databases. For example, databases like the Medical Information Mart for Intensive Care
(MIMIC)5 have enabled researchers to work with extensive datasets, surmounting regulatory
obstacles. Also, the recent DR.BENCH [36] has emerged as a new benchmark for model
development/evaluation for diagnostic reasoning based on EHRs.</p>
      <p>Furthermore, medical and clinical languages present their own complexities [37],
encompassing numerous clinical, biological, and medical subdomains, each characterized by its own
lexicon, acronyms, abbreviations, ambiguous terms, entities, and variations. To address this
challenge, some experts have developed resources such as lexicons, ontologies, and tools tailored for
medical and clinical languages. Resources like the Unified Medical Language System (UMLS) 6,
along with auxiliary tools such as MetaMap7, cTakes8 and CLAMP9, as well as adapted
advanced models and representations [38] serve as valuable assets for NLP practitioners. However,
applying these tools to analyze diverse sources like social media, which may exhibit significant
language variations, can potentially undermine the efectiveness of such tools [39].</p>
      <p>In light of the scarcity of data and the intricacies of a domain-specific language, the issue of
multilingualism assumes significance. A majority of the research eforts are oriented towards
English, likely due to the lack of available resources in other languages [40].</p>
      <p>In addition, the imperative of explainability emerges as a critical factor of contemporary
research, particularly within healthcare. The lack of interpretability undermines the acceptance
and trust of AI and NLP systems in this sensitive domain among both patients and healthcare
practitioners [41].
5https://mimic.mit.edu/
6https://www.nlm.nih.gov/research/umls/index.html
7https://lhncbc.nlm.nih.gov/ii/tools/MetaMap.html
8https://ctakes.apache.org/
9http://clamp.uth.edu/index.php</p>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusions</title>
      <p>In conclusion, this short paper ofers a bird’s eye view into the multifaceted panorama of NLP in
healthcare, showcasing its significant potential to benefit multiple stakeholders. It encompasses
patients seeking personalized health information, healthcare institutions working to streamline
their operations, physicians needing clinical decision support, and researchers delving into the
complexities of diseases, catalyzing a transformative change in the healthcare landscape.</p>
      <p>Nonetheless, NLP in healthcare extends beyond pure academic research; it is a thriving field
with real-world applications that can significantly enhance patient care. Moreover, as NLP
techniques continue to advance and adapt, an exciting frontier full of unexploited opportunities
for researchers and practitioners unfolds.
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