Self-reported generalised pruritus among community-dwelling older adults in Malaysia

In 2015, there were 2.8 million individuals aged 60 years and over in Malaysia, which comprises over 9% of its total population of 31 million [1]. Therefore, Malaysia is expected to achieve the status of an ageing nation status by 2035 when senior citizens make up 15% or 5.6 million of its population [2]. Older patients represent a unique population group with regards to skin disorders. Among individuals within the older age group, symptoms of pruritus may represent systemic disease and require a comprehensive clinical approach. Furthermore, the presence of chronic pruritus is often associated with long-term discomfort adversely affects the quality of life and psychological well-being [3, 4].

The International Forum for the Study of Itch (IFSI) classification categorises itchiness into three groups, namely: pruritus on the diseased skin (group I), non-diseased skin (group II) and secondary lesions due to pruritus (group III). Underlying diseases are classified into dermatological, systemic, neurological, psychogenic, mixed, and other causes [5]. Skin ageing increases the susceptibility to pruritic dermatoses [6]. The reduction in skin cell turnover and barrier function together with lifestyle factors such as sleep quality, stress, and diet are the factors associated with skin ageing [7].

Pruritus, or itch, is a common symptom or presentation in many systemic, dermatological, or psychological disorder. Any tissue damage or inflammation can lead to localised or generalised pruritus and pruritus can be defined as the sensation that can be relieved by scratching of the skin [8]. Published data on the prevalence of pruritus and factors associated with itch among older populations remain limited. Much of previous data focused on institutionalised residents and patients attending geriatric outpatient clinics rather than community-dwelling adults [9‐11]. An understanding of the magnitude of the problem, associated risk factors, and possible impact on the general population will aid in resource planning as well as inform clinical practice. We, therefore, determined the burden of generalised pruritus as well as factors associated with its presence and severity among the community-dwelling older population.

This study utilized data from the first and second waves of the Malaysian Elders Longitudinal (MELoR) study. The measurement of pruritus, psychological status, sleep quality and self-rated health are described below.

Six percent of our older community dwelling population aged 55 years and over reported the presence of generalised pruritus over the previous week, of which almost half described severe or very severe pruritus. The presence of pruritus was associated with lower haemoglobin levels and reduced sleep in our population.

While increasing age is associated with increased risk of multiple morbidities such as liver and renal disease with are in turn associated with itch, the presence of itch in our general older population was not found to be associated with any specific medical condition. This implies that pruritus in our older population may be primarily attributed to specific dermatoses, which may necessitate evaluation by trained physicians in order to institute appropriate treatment measures to ameliorate the symptoms. In this study, despite the significant difference in the mean haemoglobin between respondents who reported generalised pruritus and those who did not, the difference was too small to draw any clear conclusions in terms of clinical significance. This concurred with the study done by Yonova et al., where pruritus was not common among elderly people with anaemia but there is a possible role of iron deficiency [17]. As iron is implicated in the key functions of many enzymes, its deficiency may lead to alteration in enzymatic function and metabolic function with subsequent itching [18]. Cyanocobalamin levels have also been reported to be lower in patients with generalised pruritus compared to controls [19]. Hence, further research can be conducted to investigate the role iron deficiency in generalised pruritus in the elderly population. However, we were unable to proceed to test subjects for nutritional deficiencies due to funding issues and this may be an area for potential future work.

Older individuals with pruritus in our study population were not more likely to have poorer self-rated health, depression, anxiety and stress [19]. Our findings conflicted with that of other previous studies which evaluated pruritus in dermatology clinics which reported the presence of negative psychological sequelae from pruritus associated with dermatological conditions, such as prurigo nodularis, atopic dermatitis, and pruritus of unknown origin [4]. In addition, pruritus has often been cited as a distressing symptom affecting quality of life among patients with end-stage renal disease [20]. We can therefore surmise that although patients with specific dermatological conditions or chronic medical conditions associated with pruritus may experience psychological effects, this does not apply in the general older population who report the presence of generalised pruritus.

Pruritus, however, is associated with impaired sleep quality in our study which is consistent with the findings of previous studies [3]. In the absence of a direct relationship between itch and negative psychological symptoms, the negative effects of reduced sleep resulting from pruritus remains undefined in this study. Reduced sleep has been associated with reduced physical activity and reduced likelihood to go outdoors in a previous study [21]. The lack of sunlight exposure and physical exercise then further exacerbates the reduction in sleep quality. This could be due to the increment of melatonin level from adequate sun exposure and shorter sleep onset latency with regular exercise [22]. Poor sleep quality in those with pruritus may also be drug-induced. Corticosteroids [23] and first generation H1 antagonist [24] can cause hyperactivity, insomnia, and anxiety due to the blockade of acetylcholine receptors [25]. The act of scratching can also lead to lightening of sleep and a longer bout of scratching is associated with higher likelihood of subsequent arousal [26].

Our findings are limited by the cross-sectional relationship between pruritus and other associated factors. As pruritus was not recorded in the first wave of MELoR, we were unable to establish new incidence or a prospective relationship between itch and clinical outcomes. Due to resource constraints, it was not possible to assess the individuals with itch clinically to establish the underlying causes of their pruritus, and only half of the initial cohort were evaluated in the second wave due to an abrupt withdrawal of funding. Furthermore, the small number of participants with itch may also limit our ability to detect associated psychological effects. A larger study would be required to further determine the burden of pruritus in the general older population, but our findings will be vital to inform the power calculations for such a study.

Generalised pruritus is common among community-dwelling older adults aged 55 years and over and the presence of pruritus is leads to poorer sleep quality. Those with pruritus also had lower haemoglobin. Self-reported kidney and liver diseases, however, were not significantly associated with general pruritus. Future larger studies will now need to establish the likely aetiology of pruritus in the general older population to accurately determine the burden of this common condition.