Development of the PREMature Infant Index (PREMII™), a clinician-reported outcome measure assessing functional status of extremely preterm infants

Figures & data

Table 1. Participant inclusion criteria for the PREMII development stages.

PREMII development stage	Participant inclusion criteria
Clinical expert interviews	General medical license or registration, plus a specialty license or registration in neonatology, as applicable in country of origin Practicing neonatologist with ≥10 years of experience in the care of preterm infants Coauthored hospital management guidelines on the care of preterm infants or a neonatology-related textbook Oral and written fluency in English Availability for a 1-h interview and periodic consulting and/or review of short documents via email or telephone call throughout the duration of the study (∼10 months)
Delphi panel survey	General medical license or registration, plus a specialty license or registration in neonatology, as applicable in country of origin Practicing neonatologist with ≥5 years of experience in the care of preterm infants Coauthored peer-reviewed publications, hospital management guidelines on the care of preterm infants, or neonatology-related textbook; was a speaker at conferences or neonatology clinical meetings; or acted as a principal investigator/subprincipal investigator in any past or present neonatology-related trials Oral and written fluency in English Availability to complete up to three brief (10- to 15-min) online surveys
Cognitive interviews and usability testing	Practicing neonatologist with >5 years of experience in the care of preterm infants, or neonatal nurse with >5 years of experience working in the NICU Oral and written fluency in English
Online survey	General medical license or registration Specialist training in pediatrics or neonatology Practicing neonatologist or pediatrician, with responsibilities that include the care of preterm infants ≥5 years of experience in the care of preterm infants Agreement to complete a 35- to 40-min online survey in English or native language of country of origin

NICU: neonatal intensive care unit; PREMII: PREMature Infant Index.

Figure 1. Literature identification and study selection process for publications included in the targeted literature review.

Table 2. The number of articles reporting physical and nonphysical factors related to discharge readiness or length of stay in the included studies (n = 19).

Factor	Number of articles	Author(s)
Physical
Weight or weight gain	13	Barone 2014 [16]; Bender 2013 [17]; Eichenwald 2001 [18]; Gaal 2008 [19]; Hintz 2010 [20]; Jeremic 2008 [21]; Lee 2013 [22]; Manktelow 2010 [23]; Merritt 2003 [24]; Picone 2011 [25]; Seki 2011 [26]; Temple 2015 [27]; Ye 2011 [28]
Cardiorespiratory stability	11	Barone 2014 [16]; Berry 2008 [29]; Eichenwald 2001 [18]; Gaal 2008 [19]; Hintz 2010 [20]; Jeremic 2008 [21]; Manktelow 2010 [23]; Merritt 2003 [24]; Nankervis 2010 [30]; Seki 2011 [26]; Ye 2011 [28]
Oral feeding to support growth	7	Barone 2014 [16]; Eichenwald 2001 [18]; Gaal 2008 [19]; McGrath 2004 [31]; Merritt 2003 [24]; Temple 2015 [27]; Ye 2011 [28]
Ability to maintain normal body temperature or thermoregulation	5	Barone 2014 [16]; Eichenwald 2001 [18]; Merritt 2003 [24]; Seki 2011 [26]; Ye 2011 [28]
Nonphysical
Organizational	5	Eichenwald 2001 [18]; Manktelow 2010 [23]; Altman 2006 [32]; Altman 2009 [9]; Cotten 2005 [33]
Adequate home environment	2	Merritt 2003 [24]; Seki 2011 [26]
Parental readiness	1	Picone 2011 [25]

Searches were conducted using databases including Embase, MEDLINE, and PubMed for English-language articles published between 2001 and 2015. Search terms included prematurity, newborn intensive care, gestational age, scoring systems, guideline, and hospital discharge (Supplementary Tables 1–2).

Table 3. Key factors influencing discharge from NICU identified by clinical expert interviews.

Factor	Description
Feeding	Ability to feed orally to maintain consistent weight gain
Breathing	Stable respirations without positive airway pressure support
Thermostability	Ability to maintain normal temperature in open crib/bassinet
Physical/Physiological stability	Includes absence of the following: apnea, oxygen desaturation, and gastrointestinal disturbances, such as severe reflux
Retinopathy of prematurity	Stable or regressing disease
Nonphysical factors	Parental readiness, parental interaction with infant, social network support, transportation, home situation, fluency in national language/access to translation services for communication during follow-up

NICU: neonatal intensive care unit.

Figure 2. Factors important in the assessment of functional status in order of importance rating during Delphi panel survey. ^aFactors were rated on a scale of 0 (not at all important) to 5 (extremely important) and are listed in order of strength of endorsement (i.e. from highest mean importance rating to lowest). ABD: apnea, bradycardia, desaturation.

Table 4. Participant feedback from rounds 1 and 2 of the cognitive interviews, and the subsequent revisions made to the PREMII following consultation with the clinical experts.

Item		Participant feedback	Revisions to the PREMII
Respiratory support	Round 1	Suggest clarifying “no supplemental oxygen” in last level	Inclusion of a reference to negative pressure or positive pressure Definition of high-flow and low-flow oxygen included
	Round 2	“Intratracheal” not a familiar term “Negative pressure support” isn’t commonly used	Both terms removed
		“Only” doesn’t fit with instructions	Removal of “only” (to ensure that the worst level during the shift is selected)
		—	“Supplemental oxygen continuously” and “low-flow nasal cannula” split into separate levels Selection of “low-flow nasal cannula” prompts an answer on air source and greatest L/min setting
Oxygen administration	Round 1	Levels are clearer if explicit ranges are reported Distinction between > 50% and < 50% is important to capture	Incorporation of additional ranges of percentage concentrations Inclusion of instruction “report the highest concentration during each shift” (to ensure consistent and clear interpretation and completion of the item)
	Round 2	Uncertainty on how to rate the item for infants on low-flow nasal cannula	Item skipped for infants rated as being on continuous low-flow nasal cannula
Apnea	Round 1	ABD (as one item) should be separated	ABD (as one item) revised to three separate items
	Round 2	Important to clarify if infant needed intervention or not	Inclusion of “requiring intervention”
Bradycardia	Round 1	ABD (as one item) should be separated	ABD (as one item) revised to three separate items
	Round 2	Definition may change based on gestational age of the infant	No revision made
		“Clinically relevant” may cause confusion	Definitions revised
Desaturation	Round 1	ABD (as one item) should be separated	ABD (as one item) revised to three separate items
	Round 2	Important to clarify if event requires intervention or is self-resolving	Inclusion of “requiring intervention”
		Definition should include “≤”	Inclusion of “≤”
Feeding	Round 1	Need to define “oral feeds” and add/clarify regarding enteral feeding	Oral feeds defined as feeds via breast or bottle
		Suggest including reference to feeds via catheter	Inclusion of reference to enteral feeding and catheter
	Round 2	“Catheter” may cause confusion	“Catheter” removed from feeding levels
		Need to clarify “no feeds occurred”	“No feed occurred” (originally intended to represent a “not applicable” option) removed Revised to include question on whether feeds (including IV or enteral tube feeding) occurred during the shift; if “no”, item skipped
Weight gain	Round 1	Infants may not be weighed every day	Revised to account for the possibility of no weight recorded on a given day
	Round 2	—	—
Temperature	Round 1	“Bundled” not a clear or familiar term	Examples provided to define “bundled”
		Need to better highlight differences between levels Some words redundant	Reference to radiant warmer included
	Round 2	Statements wordy and too specific	No revision made

ABD: apnea, bradycardia, desaturation; IV: intravenous; PREMII: PREMature Infant Index.

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Data availability statement

All relevant data are within the paper and its supplementary information files.