In newborns, incontinence-associated dermatitis (IAD), commonly known as diaper dermatitis (DD) or nappy rash, is an inflammatory irritant lesion that manifests in areas covered by the diaper or adjacent to it.1 This irritant dermatitis is a serious problem resulting from the particular combination of moisture, maceration, friction and contact with urine, stools and other substances during the neonatal period.1,2

The development of DD is attributed to the impairment of the barrier properties of the skin in addition to the irritants themselves.3 The action of external irritants (faeces, urine, diaper material, moisture, friction)4,5 and internal factors (changes in skin pH, excessive transepidermal water losses, excessive hydration of the skin and low zinc levels)3,6 promote the development of lesions, which tend to be complicated by the action of the microorganisms present in the area.5,7,8

The incidence of IAD in the neonatal population in the community is estimated at 25%–70%.9–12 In hospitalized newborns, the reported incidence also varies widely between studies, ranging from 4.7% to 60%.13–17

The variation among studies is not limited to the reported outcomes, but also extends to the methods used to assess IAD (clinical judgment of dermatologists, clinical judgment of health care providers or use of standardised assessment scales).13–17 Stamatas et al. recommended the use of IAD severity rating scales specific to the paediatric population, as opposed to the scales used widely in the scientific literature that were developed for use in the adult population.18,19

Diaper dermatitis is a frequent iatrogenic adverse event in infants that warrants investigation of its magnitude as well as of the best methods for its clinical assessment and prevention.10,19 The lack of multicentre epidemiological studies and tools for assessment of IAD validated for use in the paediatric and neonatal population in our health system motivated us to adapt the instrument recommended by Stamatas et al. and determine the nationwide incidence of IAD in hospitalised newborns in Spain, in addition to assessing the risk factors and preventive measures associated with its development.

We undertook a study for the Spanish translation and cross-cultural adaptation of the Clinical Evaluation Scale for Characterization of the Severity of Diaper Dermatitis,18 with a subsequent assessment of its content validity, leading to the conclusion that the Spanish version is a valid instrument to grade DD in the neonatal population of Spain. A literature review conducted by Dunk et al.19 in 2022 identified as many as 8 instruments used for the assessment of DD in the paediatric population in different studies, which results in inconsistencies in the language and criteria applied to its definition and grading and hinders the comparison of data from different studies.23 In Spain, the Clinical Evaluation Scale for Characterization of the Severity of Diaper Dermatitis is the first instrument validated for the neonatal population. In their reviews, Esser and Dunk concluded that the availability of validated scales would allow the standardization of definition criteria, measurement of the frequency of IAD, assessment of its severity and evaluation of treatment outcomes.19,23 The heterogeneity of the instruments used for the same purpose, validated in different countries and applicable to different age groups makes it difficult to generalise research findings. International initiatives like the Ghent Global Incontinence Associated Dermatitis Categorization Tool (GLOBIAD), validated in 30 countries for use in the adult population, exemplifying how validation processes should be undertaken in the future. The use of a single scale, modified, adapted and validated in both the adult and paediatric populations would facilitate its clinical application through the standardization of diagnostic criteria and the effective management of the preventive resources available in health care facilities.24,25

Applying the dermatitis severity rating scale in multiple centres, we found that 3 out of 10 hospitalised neonates had some degree of IAD. The incidence of IAD reported by studies in hospitalised neonates is variable. The studies of Meszes et al.16 and Csoma et al.,15 in which dermatitis was assessed by a dermatologist, found an incidence of 4.7% (n = 211) and 5.4% (n = 460), respectively. Visscher et al.,14 in a study in which the assessment was made by nurses using standardised numerical scales for erythema and dryness and physiological measures, found an incidence of 60% (n = 130). Alonso et al.13 reported an innocence of 19.7% (n = 213) based on the assessment by paediatricians and the application of the scale proposed by Lane and Drost modified by Kiechl-Kohlendorfer. Malik et al.17 carried out a retrospective in 1241 hospitalised newborns and found an incidence of DD of 23% based on the documentation in the health records. The heterogeneity in the assessment approaches hinders the comparison of our findings with those of previous studies. The high percentage of cases categorised as mild (71.4%) may not have been considered IAD in assessments based on the clinical judgment of the provider. We consider that early detection of this type of lesions is important in clinical practice, for, as our findings illustrate, preventive measures like the use of barrier products (containing zinc oxide, silicone or polyurethane, fatty acids, etc) behaved as risk factors in our analysis because they were not implemented until the rash was detected.

As regards the factors associated with IAD in our study, gestational age, sex or birth weight were not significantly associated with it. This was consistent with the findings of previous studies in which the fragility of the skin of preterm infants did not seem to be associated with an increase in IAD, and the frequency of IAD episodes was higher with increasing age in weeks.13,14,26 In our sample, the length of admission and the chronological age at discharge were significantly greater in the IAD group. In the previous literature, this direct correlation between the weeks of age and the frequency of IAD episodes has been found to be associated with an increase in the number of bowel movements and urine output,13,14,26 which in our study were also significantly greater in the IAD group.

When it came to the pH, we did not find significant differences in the mean (quantitative) faecal or urine pH during the stay between groups. Other studies considered the pH of the skin covered by the diaper14,26,27 and found a more alkaline pH, a factor that is associated with the development of IAD. Since the mean pH in urine and in faeces at admission was approximately 6, we decided to assess how many newborns had means 0.5–1 point above or below this pH value, and found that a significant percentage of newborns with dermatitis had a faecal pH of less than 5.5 or greater than 7. The damage to the skin probably depends more on significant fluctuations toward greater acidity as well as alkalinity of the eliminated waste. We did not find evidence of this association between pH and IAD for urine, which made us consider the possibility that the irritant that has an impact on the faecal pH is not at play in urine.

When we assessed the association between pharmacological treatment and the presence of dermatitis, we found an increased risk in neonates who received oral therapy (nutritional supplements, antibiotherapy, antifungal therapy, etc). While other authors had already proposed the association between antibiotherapy and the development of dermatitis,28 our findings expand the scope of the association to other types of oral drugs. We found that oral drugs of any time were used more frequently in newborns with IAD. The significantly higher frequency of IAD observed in newborns who received vitamin D supplementation may have been biased on account of age, since the age in days at discharge was significantly greater in neonates who received vitamin D supplementation compared to newborns who did not receive it (22.2 vs. 11.16 days; P = .000).

We assessed the feeding modality in neonates, and found that the frequency of dermatitis was significantly greater in those who received mixed feeding and significantly lower in those who received exclusive breastfeeding. Similarly, the study conducted by Ersoy-Evans et al.29 in a community-based sample of 63 children aged 0–24 months with dermatitis of varying severity found that those who had been breastfed had had fewer episodes of dermatitis. The authors attributed this to a lower faecal pH (5.28 in the breastfed group compared to 6.82 in the formula-fed group) and the faecal lower lipase and protease activity in the breastfed group,29 which was consistent with the findings of Berg et al.,6 who analysed frozen specimens obtained from 20 infants in the community aged 1–5 months, of who 10 were exclusively breastfed. In our study, we calculated the mean urine and faecal pH measured daily during the stay at the time of excretion, and found a significantly lower pH in the faeces of exclusively breastfed neonates. However, these infants also had a significantly higher urine pH. On the other hand, mixed feeding, a clear risk factor in the study, was not associated with significant differences in the faecal pH in comparison with the exclusive breastfeeding group. The patient age range, sample size and other conditions in the studies conducted by Ersoy-Evans et al.29 and Berg et al.6 differed significantly from our study, which could explain the observed differences. We searched for statistically significant differences based on the feeding modality groups in our sample, and found a more alkaline urine pH in the exclusively breastfed group and a higher proportion of infants who had used collection bags during the hospital stay in the mixed feeding group. In our opinion, these are relevant factors, but they cannot justify a protective effect or an increased risk associated with different feeding modalities. At present, there is no clear evidence of the association of early introduction of formula feeding or mixed feeding with other cutaneous disorders, such as atopic dermatitis.30,31 It would be interesting to explore whether the known differences or changes in in the microbiota in association with the feeding modality (differences in the concentration of short-chain fatty acids and in the composition of the microbiota)32–34 could be related to our findings.

As newborn infants develop, the frequency of urination and bowel movements increases and this in turn increases the risk of IAD due to a greater exposure to irritants.

Newborns hospitalised in neonatal units or neonatal intensive care units with an increased stool frequency, who receive mixed-feeding, who receive oral drugs or carry medical devices in the perianal area (collection bags) are at increased risk of developing diaper dermatitis, so the preventive use of barrier products is indicated in these patients.

On the other hand, barrier products are used more frequently after the detection of dermatitis than for preventive purposes. The use of clinical prediction rules for dermatitis can help detect IAD in its early stages and promote the early use of these products to prevent progression to more severe stages.

This research project did not receive specific financial support from funding agencies in the public, private or not-for-profit sectors.

The study was approved by the Clinical Research Ethics Committee of each participating hospital. Parents and/or legal guardians received an informational sheet and were asked to sign an informed consent form (and informed of the ability to withdraw consent at any time). The study did not include any data that could be used directly or indirectly to identify the patient, in adherence with Organic Law 3/2018, of December 5, on the Protection of Personal Data and the Guarantee of Digital Rights. The researchers in each of the participating centres were responsible for ensuring the safety of the collected data, which were to be accessed and used solely for the established purposes of the study.

We submitted the study protocol to the Agencia Española de Medicamentos y Productos Sanitarios (AEMPS, Spanish Agency of Medicines and Medical Devices), which classified it as a “non-post-authorization observational study”.

The authors have no conflicts of interest to declare.