help bronch-------------------------------------------------------------------------------

Title

bronch-- Calculates severity of illness in bronchiolitis using the National Children's Hospital severity of bronchiolitis model, (NCH-SOB).

Syntax

[ work_of_breathing tachycardia age dehydration] {if} [bronch,options]

[ work_of_breathing tachycardia age dehydration] {if} [bronchi,options]

optionsDescription ------------------------------------------------------------------------- Mainnchuses coefficients based on an inpatient derivation dataset, the defaultolhscuses coefficients based on an emergency department validation datasetscreensends the output to a printeradmitcalculates the probability of admissiondischargecalculates the probability of dischargeprobabilitiescalculates the probability of a patient falling into another severity category -------------------------------------------------------------------------

Description

bronchcalculates the severity of illness for infants presenting with bronchiolitis. It relies on four variables age(in months), dehydration classified as none(0) mild(1) moderate(2) or severe(3), tachycardia (heart rate at or above the 98th centile for age), Increased work of breathing defined as (1)for moderate or severe increase in work of breathing and (0) otherwise. This command categorizes bronchiolitis severity as mild, moderate or severe using an ordinal logistic regression model.bronchexpects data in the wide format i.e. one observation per row and all the required variables in that row. When issuing bronch the order in which the variables are specified matters. After executingbronchstata issues a warning to the user reminding them which variable has been used to specify each component in the model. It is the user's to ensure that they have correctly specified the variables used to calculate the score.

Options+------+ ----+ Main +-------------------------------------------------------------

nchuses coefficients based on an inpatient derivation dataset. This is the default. The coefficients (odds ratio)for this option are as follows. Age *** ()per month, Dehydration ***() per step increase from none,mild, moderate, severe, Tachycardia ** (), Increased work of breathing** ()

olhscuses coefficients based on an emergency department validation dataset. The coefficients (odds ratio)for this option are as follows. Age *** ()per month, Dehydration ***() per step increase from none,mild, moderate, severe, Tachycardia ** (), Increased work of breathing** ()

probabilitiescalculates the proabability for each observation falling within each bronchiolitis severity classification (mild, moderate, severe). This option creates three new variables for each observation _pmild _pmoderate and _psevere containing the values for the mild moderate and severe categories respectively.

admitcalculates the proabability for each observation of not having mild disease. This is the probability of admission when using theohlscoption and the probability of being discharged in less than one day with thenchoption. This option creates a new variable for each observation _padmit.

printscreensends the output to the screen.

generate(newvar)createsnewvarcontaining the value for bronchiolitis severity.If not specified the default is bronch.

Saved Results+---------+ ----+ Support +----------------------------------------------------------

_bronchcontains the severity of bronchiolitis (i.e. mild, moderate, or severe)

_pmildcontains the probability of mild disease

_pmoderatecontains the probability of moderate disease

_pseverecontains the probability of severe disease

_tachycardia_productcontains the product of the coeficient (odds ratio) of tachycardia and the record value for each observation

_age_productcontains the product of the coeficient (odds ratio) of age and the record value for each observation

_dehydration_productcontains the product of the coeficient (odds ratio) of dehydration and the record value for each observation

_work_of_breathing_productcontains the product of the coeficient (odds ratio) of work of breathing and the record value for each observation

_Zcontains the summation of the products of the four parameters for each observation

_Z_difference_Zi_k1contains the data that corresponds to mild disease for each observation

_difference_Zi_k2contains the data that corresponds to both mild and moderate disease for each observation

_probability_Zi_k2contains the combined probability of mild and moderate disease for each observation

_logit1_1contains the probability of mild disease

_logit2_1contains the probability of moderate disease

_logit3_1contains the probability of severe disease

_padmitcontains the probability of admission using anything greater than mild disease as a surrogate marker for a patient that should be admitted

_dischargecontains the probability of discharge using mild disease as a surrogote marker for a dischargable patient

_wob_processedcontains a simplified version of the mapped work of breathing data

_wob_processed_modcontains the mapped work of breathing data as described in the algorithm in reference 1

_age_processedcontains the mapped age data as described in the algorithm in reference 1

_dehyd_processedcontains the mapped dehydration data as described in the algorithm in reference 1

_tachy_processedcontains the mapped tachycardia data as described in the algorithm in reference 1

_missing_wobcontains the number of observation with missing data for work of breathing

_missing_agecontains the number of observation with missing data for age

_missing_tachycontains the number of observation with missing data for tachycardia

_missing_dehydrationcontains the number of observation with missing data for dehydration

_valid_calculationcontains the number of observation with valid data

RemarksThe NCH-SOB was derived in one childrens hospital where mild was defined as im > mediate discharge on review of the resident admission by an attending pediatrician, mo > derate as hospital admission less than and including median length of stay, and severe d > isease as admission greater than the median length of stay. The model was validated in a > nother childrens hospital Emergency Department. In the validation 'mild' severity was > based on actual discharge from the pediatric emergency room by a resident with at leas > t five years post graduate training. 'Moderate' disease was defined as hospital admission > less than and including median length of stay, and 'severe' disease as admission for greater > than the median length of stay. The median length of stay was the same in both derivati > on and validation phases. Both models satisfied the proportional odds assumption. Users may select which > coefficents to use based on whether they are dealing primarily with inpatient or outpatien > t data. Full details of the model used in this severity of illness classification tool can > be found in reference 1.

Examples

. bronchi mild 150 2 mild

. bronch work_of_breathing tachycardia age dehydration

. bronch work_of_breathing tachycardia age dehydration , olhsc prob admit

. bronch work_of_breathing tachycardia age dehydration, by(gender)

AuthorsCarl E. Mitchell Department of Emergency Medicine Kern Medical Center Bakersfield, CA 93306

Paul Walsh Department of Emergency Medicine Kern Medical Center Bakersfield, CA 93306

ReferencesWalsh, P. Rothenberg, S.J., O'Doherty, S., Hoey, H. and Healy, R. 2004 A va > lidated clinical model to predict the need for admission and length of stay in children with ac > ute bronchiolitis.

European Journal of Emergency Medicine11:5 265-72