The sample of 133,025 patients with AD (Table 2) consisted of 69,551 (52.3%) children (age less than 18 years) and 63,474 (47.7%) adults (age 18 years or older). The average age was 5.9 years (SD = 5.0) for children and 49.9 years (SD = 19.3) for adults. Overall, slightly over half of the patients were female (55.7%). To the extent that race/ethnicity is recorded in the EHR, the majority were white and non-Hispanic. Primary care and pediatric practices accounted for the most patients (39.9% and 35.7% of all AD cases, respectively). Allergists and immunologists provided care for 11.2% of patients with AD, and dermatologists accounted for 7.2%. This contrasts with the nearly 2:1 ratio of dermatologists to allergists/immunologists in the USA [14] and is reflective of the composition of the user base of the EHR.

Records were examined for the prevalence of six AD-associated comorbidities (Table 3). Regardless of age, the most common documented comorbidity was allergic rhinitis (23.9%). The condition was slightly more common among children (26.0%) than adults (21.5%). Asthma was also widely diagnosed (15.2%), at similar rates among children (15.9%) and adults (14.4%). Rhinosinusitis was slightly more prevalent among adults (4.0%) than children (2.1%), while food allergies were more often seen in children (6.7% vs. 1.7% for adults).

The use of AD-related medications as of the index visit is reported in Table 3. Topical corticosteroids were the most widely prescribed (58.6% of the sample), with 60.8% of children and 56.1% of adults having a prescription. Oral antihistamines (20.9% of the sample) and oral corticosteroids (19.5%) were the next most widely prescribed medications. Oral corticosteroids were more commonly prescribed for adults (23.1%) than for children (16.2%). Oral antihistamine prescriptions were found in similar proportions of adults and children (20.5% and 21.3%, respectively). Injectable biologics (IgE or IL-4/IL-13 inhibitors) and conventional oral immunosuppressants (azathioprine, cyclosporine, methotrexate, mycophenolate mofetil, tacrolimus) were prescribed to less than 1% of patients, generally adults. No patients were on interferon gamma treatment.

Over a third of the patient sample had a prescription from a single class of drugs (39.8%). Less than 10% of the sample had prescriptions from three or more classes. Patients seeing allergists/immunologists more often had three or more drug classes (10.1%) than those seeing dermatologists (4.1%), PCP-pediatrics (7.2%), or PCP-adults (8.8%) (Table 4). Over one-third of children (37.5%) and a quarter of adults (26.2%) had no record of a prescription for an AD-related medication. This included approximately one-third of patients seeing allergists/immunologists (34.7%), dermatologists (34.7%), PCP-pediatrics (31.3%), and PCP-adults (27.4%). Most patients seeing other specialties had no AD-related medications (60.4%).

Table 5 summarizes the occurrence of disease, treatment, symptom, and work/lifestyle-related terms in provider notes. Disease-related and treatment terms were documented in 28% of patient notes. They were not well documented for children (0.3%), but occurred for over half of adult patients (58.3%). Disease-related and treatment terms were most often mentioned for patients of dermatologists (60.9%) and PCPs treating adults (43.1%). In contrast, PCPs treating children mentioned them less often (2.5% of patients). The specific topics most often documented were related to the general atopic nature of the condition (25.6% overall, 53.4% for adults). Dermatologists documented these topics for over 50% of their patients, followed by PCPs with adult patients (39.2%).

Symptoms (itch, neuralgia, pain, sleep) were the predominant note content (39.0% of all patients). Allergists/immunologists and dermatologists provided the most symptom-related information (61.1% and 65.3% of patients, respectively) followed by PCPs (35.3% of adult patients, 30.0% of pediatric patients). The most heavily documented term was itch (37.6% of all patients, 34% of children, 41.5% of adults), mentioned for nearly two-thirds of allergists’/immunologists’ and dermatologists’ patients, and for nearly one-third of PCP patients. Neuralgia, skin pain, and sleep disturbances were each mentioned for less than 2% of patients, regardless of patient age. HCPs from the “other specialties” category, such as those who do not have a specialty noted or podiatrists, naturopaths, or nurse practitioners, tended to document these topics more often (neuralgia 4.4%, pain 7.0%). Sleep issues were not often mentioned (0.3% of children and 0.6% of adults) and more often occurred in allergist/immunologist notes (0.8%) than in other specialties.

Personal terms related to lifestyle or work were rarely documented (0.5% of all patients). Documentation of the personal aspects of AD were almost never recorded for children, and life issues were rarely mentioned in adults’ notes (0.4%). Work-related terms came up slightly more frequently (0.7% of adult patients). Allergists/immunologists were somewhat more likely to make notes regarding personal topics (lifestyle 0.8%, work 0.9%), followed by dermatologists (0.7% and 0.5%, respectively).

Figure 1 presents the bigram analysis for “itch”, the most heavily documented symptom assessed (37.6% of all patients). Sentences dealing with itch focus largely on related symptoms (rash, burn, redness, swelling, congestion, lesions), treatment (hydroxyzine, topical, cream), or more general terms (patient, skin, change, atopic, dermatitis). As suggested by the counterclockwise relative locations of the terms, symptoms were mentioned somewhat more often than treatments. Bigrams occurred in “itch” sentences not involving the keyword—these are indicated by connections between non-nodal terms on the graph and include “skin rash”, “dry skin”, “dry redness”, and “atopic dermatitis”.

Bigram network for “itch”. PRN pro re nata (as needed)

The atopic characteristics of AD were the second most widely documented topic (25.6% of all patients). Figure 2 bigrams show “atopic” is mentioned most often in relationship with words describing the skin (eczema, dermatitis, skin, rash), severity (severe, mild, acute, improvement), complications (neuralgia, neuritis), or treatment (ointment, topical). Other bigrams occurring in atopic sentences indicate conferences with patients (“patient discussion”), treatments (“topical ointment”), and discomfort (“neuralgia neuritis”).

Bigram network for “atopic”

Treatment-related terms are the primary subjects dealt with by the “topical” term (Fig. 3). Words related to this term include ointment, cream, lotion, hydrocortisone, treatment, medication, and bath. Symptoms (rash, itch, stop) are also related to the term, as are several general terms (infect, atopic, dermatitis).

Bigram network for “topical”

Figure 4 shows bigram relationships having to do with systemic treatment. “Systemic” forms significant bigrams with terms related to management and treatment (reaction, steroid, treatment) as well as terms related to signs and symptoms (symptom, blister, red, erythema). Other bigrams (steroid with topical, include, patient, PRN) reflect a concern with both treatment and its expected benefits (benefit with risk, benefit with immunotherapy).

Bigram network for “neuralgia”. PRN pro re nata (as needed)