NLM Classification 2022 Summer Edition Now Available

The NLM Classification was updated on August 31, 2022. NLM is committed to regularly updating and revising the NLM Classification based on advancements in science and current events. Each year NLM selects portions of the classification schedules for systematic review and revision.

The major focus of the 2022 summer edition was the systematic review of the following schedules: WF Respiratory System and WH Hemic and Lymphatic Systems. In addition to the systematic reviews of the WF and WH schedules, other minor additions and changes were made.

Summary Statistics for the 2022 Summer Edition

• 35 class numbers added
• 2 schedule range headers added
• 78 class number captions or notes modified
• 8 schedule range headers modified
• 4 class numbers canceled
• 1 schedule range headers deleted
• 31 index main headings added
• 199 index entries modified
• 46 index headings deleted

Systematic Reviews for the 2022 Summer Edition

Highlights from the WF Respiratory Systematic Review

• 19 NEW WF CLASS NUMBERS

New Class Number	Caption
WF 105	Respiration
WF 140.3	Respiration disorders
WF 140.5	Respiratory insufficiency
WF 140.7	Respiratory system infections
WF 141.5.L9	Lung volume measurements
WF 141.5.S8	Spirometry
WF 144	Apnea
WF 146	Artificial respiration
WF 148	Oxygen inhalation therapy
WF 235	Therapy
WF 302	Epidemiology (Table-G)
WF 302.1	[Epidemiology] General coverage (Not Table-G)
WF 304	Pathology
WF 306	Diagnosis
WF 555	Pediatric
WF 610	Anatomy. Histology. Embryology. Congenital abnormalities
WF 620	Physiology
WF 630	Lung diseases (General)
WF 972	Thoracic diseases
WU 511	Crowns

• 4 CANCELED WF CLASS NUMBERS

Deleted Class Number	Former Caption	New Instructions for Classification
WF 225	Mass chest X-ray	Classify works on mass chest X-ray in WF 975
WF 290	Lymph node tuberculosis. Scrofula	Classify works on lymph node tuberculosis in WH 700
WF 405	Tuberculosis in the workplace	Classify works on occupational exposure to tuberculosis in WF 200-WF 390
WF 805	Functional disorders	Classify works on functional disorders of diaphragm in WF 800

• 36 MODIFED WF CLASS NUMBERS
• 6 MODIFED CLASS NUMBERS IN OTHER SCHEDULES RELATED TO WF SYSTEMATIC REVIEW

Highlights from the WH Hemic and Lymphatic Systems

• 11 NEW WH CLASS NUMBERS

New Class Number	Caption
WH 173	Sickle cell anemia
WH 220	Lymphocytes
WH 260	Lymphoid leukemia
WH 265	Myeloid leukemia
WH 305	Hemostasis
WH 311	Fibrinolysis and associated blood proteins
WH 382	Bone marrow transplantation
WH 383	Hematopoietic stem cells. Hematopoietic stem cell transplantation
WH 470	Blood donation. Blood donors
WH 490	Hematologic neoplasms (General)
WH 720	Lymphatic diseases (General)

• NO CANCELED WH CLASS NUMBERS
• 22 MODIFED WH CLASS NUMBERS
• 1 MODIFED CLASS NUMBER IN OTHER SCHEDULES RELATED TO WH SYSTEMATIC REVIEW

Additional Changes

Several classification issues were investigated and resolved.

Issue	Resolution
Where to class non-human models as well as anatomic models of plants?	Added Sub-Indexes (SIs) for animal and comparative anatomy of humans and animals to index record for Models, Anatomic. Also added SI for anatomic models of plants.
Where to class the new 2022 Medical Subject Headings (MeSH) Epidemiological Models which is not in the index. It trees under Models, Biological which is classed in QH but probably better classed in NLM classification.	Epidemiological Models was added to index classed at WA 950. Adjusted header above WA 950 to add Epidemiologic Methods.
Where to class Models, Immunological? The parent term, Models, Biological points to QH 324.8.	Added Models, Immunological to the index classed at QW 26.5.
Where to class Epigenomics: QU 460 with the broader term of Genomics or QU 475 based on the scope note?	Created new number QU 476 Genetic Epigenesis. Epigenomics indented under QU 475. Reclassified pertinent child terms. Added note to QU 460: Classify epigenomics at QU 476.
Where to class Birth Setting? Its parent term, Parturition, is classed at WA 300. Its child term, Home Childbirth, is classed at WQ 155.	Added Birth Setting to the index classed at WQ 155. Changed the caption at WQ 155 to broaden it from Home childbirth.
Where to class contact tracing in general? Currently the index only has guidance for contact tracing of sexually transmitted diseases.	Added SI General WA 110 under Contact Tracing.
Domestic Violence is classed at WA 308 which is captioned Family Health. These are very different subjects.	Family Violence (the MeSH Entry Term for Domestic Violence) was added to the caption at WA 308.
Where to class psychology of athletes. Should it be classed in WA 305 for mental health issues of special groups or with Sports Medicine in QT 260?	Created new number for Sports psychology at QT 264. Added to index: Psychology, Sports QT 264. Add SI Psychology QT 264 to index terms: Athletes Athletic Performance
The only class number for Speech Intelligibility is in WM. Speech Intelligibility is treed under Speech. Need a general number.	Classed Speech Intelligibility only with Speech at WV 501.
Where to class collective biographies of traditional healers?	Created new number for Collective Biography of Traditional Healers WZ 112.5.T7. Added SIs for this new number under all Traditional Medicine terms since there currently are no person terms in MeSH.
Where to class works on broad urogenital diseases that cover kidney, upper urinary tract, bladder, urethra, prostate, testis, penis, scrotum and adrenal gland. Currently the index for Urogenital Diseases points to WJ 700 which is general works on Male Genitalia.	The range header above WJ 140 and the caption at WJ 140 were broadened from Urologic Diseases to Urogenital Diseases. Added note at WJ 140 to classify genital diseases at WJ 700.  Adjusted index record for Urogenital Diseases.
Should Vascular Diseases $x surgery be classed at WG 170 for Vascular surgical procedures or WG 505 for Vascular diseases (General or not elsewhere classified)?	Added SI Surgery WG 170 to index record for Vascular Diseases.
Infanticide and Abortion, Criminal are both classed at W 867 but they are unrelated concepts. Infanticide trees only under Homicide. Abortion, Criminal is a sister term to Homicide, but does not tree under it.	Removed Infanticide from W 867 caption.  Reclassified Infanticide with Homicide.
Review physical examination WB area to evaluate accuracy of classification and completeness.	A mini-systematic review of the WB 205-WB 286 Physical examination area was conducted. Several WB captions were changed to reflect the technique (e.g., Blood pressure was changed to Blood pressure determination). Terms treeing in the MeSH tree Physical Examination [E01.370.600] were evaluated. Several index terms were added (e.g., Respiratory Rate).

Next Edition

The 2023 winter edition will be published in late January 2023. It will encompass the additions and changes from the 2023 MeSH vocabulary as evaluated for inclusion in the Classification index. All main index headings will be linked to the 2023 vocabulary in the MeSH Browser at that time.

The NLM Classification number appears in many terms in the MeSH browser and is supplied by the Cataloging and Metadata Management Section (CaMMS) when the MeSH term points to a single classification number. These class numbers are current as of the Winter 2022 edition of the NLM Classification. They will be updated with the publication of the 2023 Winter edition in January 2023.

To learn more about the NLM Classification see the NLM Policy on Classification.