Letter: Sickling pain and season

Peripheral transient receptor potential vanilloid type 4 hypersensitivity contributes to chronic sickle cell disease pain

ABSTRACT

Debilitating pain affects the lives of patients with sickle cell disease (SCD). Current pain treatment for patients with SCD fail to completely resolve acute or chronic SCD pain. Previous research indicates that the cation channel transient receptor potential vanilloid type 4 (TRPV4) mediates peripheral hypersensitivity in various inflammatory and neuropathic pain conditions that may share similar pathophysiology with SCD, but this channel's role in chronic SCD pain remains unknown. Thus, the current experiments examined whether TRPV4 regulates hyperalgesia in transgenic mouse models of SCD. Acute blockade of TRPV4 alleviated evoked behavioral hypersensitivity to punctate, but not dynamic, mechanical stimuli in mice with SCD. TRPV4 blockade also reduced the mechanical sensitivity of small, but not large, dorsal root ganglia neurons from mice with SCD. Furthermore, keratinocytes from mice with SCD showed sensitized TRPV4-dependent calcium responses. These results shed new light on the role of TRPV4 in SCD chronic pain and are the first to suggest a role for epidermal keratinocytes in the heightened sensitivity observed in SCD.

Environmental Factors in Northern Italy and Sickle Cell Disease Acute Complications: A Multicentric Study

BACKGROUND

Environmental factors seem to influence clinical manifestations of sickle cell disease (SCD), but few studies have shown consistent findings. We conducted a retrospective multicentric observational study to investigate the influence of environmental parameters on hospitalization for vaso-occlusive crises (VOC) or acute chest syndrome (ACS) in children with SCD.

METHODS

Hospital admissions were correlated with daily meteorological and air-quality data obtained from Environmental Regional Agencies in the period 2011-2015. The effect of different parameters was assessed on the day preceding the crisis up to ten days before. Statistical analysis was performed using a quasi-likelihood Poisson regression in a generalized linear model.

RESULTS

The risk of hospitalization was increased for low maximum temperature, low minimum relative humidity, and low atmospheric pressure and weakly for mean wind speed. The diurnal temperature range and temperature difference between two consecutive days were determined to be important causes of hospitalization. For air quality parameters, we found a correlation only for high levels of ozone and for low values at the tail corresponding to the lowest concentration of this pollutant.

CONCLUSIONS

Temperature, atmospheric pressure, humidity and ozone levels influence acute complications of SCD. Patients' education and the knowledge of the modes of actions of these factors could reduce hospitalizations.

Effect of Weather on Frequency of Vaso-Occlusive Crisis in Children With Sickle Cell Disease

Introduction Sickle cell disease (SCD) is characterized by acute vaso-occlusive crisis (VOC) often manifested as painful episodes. Environmental factors are known to play a role in the frequency and severity of VOC. Methods The aim of this study is to analyze the relationship between weather changes and VOC in children with SCD. Data on daily temperature, humidity, and wind speed in Brooklyn, New York was collected over one year. Daily census data of children < 20 years of age with SCD presenting with VOC during the study period was retrieved from the Health Information Systems database. Data was analyzed to determine correlations of daily temperature, humidity, and wind speed with the number of VOCs using Pearson correlation co-efficient and time-series statistics. Results The total number of episodes of VOC was 344, with 218 outpatients and 126 inpatients. Total episodes of VOC peaked during January (n=44), while they were lowest in July (n=16). We observed a negative correlation of VOC with temperature (r= -0.05, p=0.04) and no correlation with humidity (r=0.01, p=0.85) was noted. Analysis of wind speed showed a negative correlation with VOC which is not significant. Conclusion No significant correlation was found between changes in humidity or wind speed and VOC. As this study was performed in an urban environment with extreme weather changes, results may be different in other geographic areas.

Cold External Temperatures and Sickle Cell Morbidity in Children: A Retrospective Analysis

BACKGROUND

Genetic and environmental factors affect the occurrence of vaso-occlusive crises (VOCs) in patients with sickle cell disease (SCD). Research provides inconsistent evidence on how environmental temperature affects SCD. Edmonton, Alberta, has an increasing SCD population and is the northern-most city in North America with a population of over a million.

OBJECTIVE

The objective of this study was to identify whether pediatric patients with SCD experience increased morbidity in cold external temperatures.

MATERIALS AND METHODS

This study was a retrospective case series. Emergency visits, phone calls, and admission data for VOC in children were recorded from July 2011 to June 2016. Temperatures were recorded and statistically analyzed using descriptive statistics, to determine the relation to VOC.

RESULTS

A total of 118 patients with 257 VOC events were reviewed. When analyzing the mean, minimum, and change in temperatures at presentation, the largest percentage of VOC events occurred at mild to moderate temperatures. Temperature data at 24 and 48 hours before the presentation had similar results. When accounting for the relative frequency of extreme weather days, there are increased VOC events with temperature fluctuations >20°C.

CONCLUSIONS

There was no correlation between mean and minimum temperature change. Fluctuation in temperature of >20°C was associated with increased relative VOC frequency, suggesting that large temperature variability should be avoided in SCD, but a prospective study is required to determine causality.

Sickle Cell Disease and Infections in High- and Low-Income Countries

Infections, especially pneumococcal septicemia, meningitis, and Salmonella osteomyelitis, are a major cause of morbidity and mortality in patients with sickle cell disease (SCD). SCD increased susceptibility to infection, while infection leads to SCD-specific pathophysiological changes. The risk of infectious complications is highest in children with a palpable spleen before six months of age. Functional splenectomy, the results of repeated splenic infarctions, appears to be a severe host-defense defect. Infection is the leading cause of death, particularly in less developed countries. Defective host-defense mechanisms enhance the risk of pneumococcal complications. Susceptibility to Salmonella infections can be explained at least in part by a similar mechanism. In high-income countries, the efficacy of the pneumococcal vaccine has been demonstrated in this disease. A decreased in infection incidence has been noted in SCD patients treated prophylactically with daily oral penicillin. Studies in low-income countries suggest the involvement of a different spectrum of etiological agents.

Children and adolescents with sickle cell disease have worse cold and mechanical hypersensitivity during acute painful events

Sickle cell disease (SCD) pain associates with cold temperature and touch. Patients and murine models with SCD have baseline thermal and mechanical pain. In SCD mice, the baseline hypersensitivity is exacerbated by experimental vaso-occlusive crises. We hypothesized that patients with SCD will similarly experience increased hypersensitivity to thermal and mechanical stimuli during acute painful events compared with baseline health. We conducted a prospective study of 24 patients with SCD aged 7 to 19 years. Patients underwent quantitative sensory testing to thermal (cold/heat) and mechanical stimuli on the thenar eminence of the nondominant hand (glabrous skin) and the lateral dorsum of the foot (hairy skin) during baseline health and within 48 hours of hospitalization for acute pain. Primary outcomes were changes in: (1) cold pain threshold (°C), (2) heat pain threshold (°C), and (3) mechanical pain threshold (g). Median age was 10.5 (interquartile range [IQR] 9-14.8) years, 67% were females, and 92% were on hydroxyurea. Patients with SCD had increased cold pain sensitivity in the hand during hospitalization compared with baseline (25.2°C [IQR 18.4-27.5°C] vs 21.3°C [IQR 4.9-26.2°C]; P = 0.011) and increased mechanical pain sensitivity in the foot during hospitalization (0.32 g [IQR 0.09-1.1 g] vs 1.7 g [IQR 0.4-8.3 g]; P = 0.003). There were no differences in heat pain sensitivity. The increased cold (P = 0.02) and mechanical (P = 0.0016) pain sensitivity during hospitalization persisted after adjusting for age, sex, hydroxyurea use, opioid consumption, and numeric pain score. Thus, cold and mechanical pain is significantly worse during an acute SCD painful event as compared to baseline health in patients with SCD.

Predictors of mortality in adults with Sickle cell disease admitted to intensive care unit in Bahrain

OBJECTIVE

Sickle cell disease (SCD) is one of the most common genetic blood disorders in Bahrain. However, there is a paucity of data regarding the clinical presentation of SCD patients who require ICU admission. This study aimed to describe the epidemiological data of SCD patients admitted to the ICU and to identify predictors of mortality in order to help intensivists identify patients at most risk.

METHOD

This study used a retrospective, descriptive, and correlational design. Records of 210 SCD patients admitted to the ICU in Salmaniya Medical Complex (SMC) were reviewed.

RESULTS

210 patient with SCD were admitted to ICU during study period. The main reason for ICU admission was acute chest syndrome. The mortality rate of SCD patients in the ICU was 12.7%. The four significant predictors of mortality were age, number of previous hospitalizations, length of stay, and need of renal replacement therapy. Non-survivors were older than survivors (M=38.6 vs. M=30.3years, U=1685, z=-2.2, P=0.025), were less frequently hospitalized (M=19 vs. M=46 times, U=1274, z=-3.7, P=0.000), had shorter lengths of stay in the ICU (M=3.1 vs. M=5.5days, U=1145, z=-4, P=0.000), and more likely to require renal replacement therapy the p=0.0297 than the survivors. The combined effect of these predictors was modelled with cox regression and found to be statistically significant. Gender, presence of comorbid conditions, level of hemoglobin on admission, and need for blood transfusions were not found to be predictors for mortality.

CONCLUSION

Acute chest syndrome was the main reason for SCD patients to be admitted to the ICU. Older age, less frequent hospitalization, shorter stays in the ICU, and the need for renal replacement therapy were found to be indicators of high mortality rate SCD patients.

Sensitization of nociceptive spinal neurons contributes to pain in a transgenic model of sickle cell disease

Chronic pain is a major characteristic feature of sickle cell disease (SCD). The refractory nature of pain and the development of chronic pain syndromes in many patients with SCD suggest that central neural mechanisms contribute to pain in this disease. We used HbSS-BERK sickle mice, which show chronic features of pain similar to those observed in SCD, and determined whether sensitization of nociceptive neurons in the spinal cord contributes to pain and hyperalgesia in SCD. Electrophysiological recordings of action potential activity were obtained from single identified dorsal horn neurons of the spinal cord in anesthetized mice. Compared with control HbAA-BERK mice, nociceptive dorsal horn neurons in sickle mice exhibited enhanced excitability as evidenced by enlarged receptive fields, increased rate of spontaneous activity, lower mechanical thresholds, enhanced responses to mechanical stimuli, and prolonged afterdischarges following mechanical stimulation. These changes were accompanied by increased phosphorylation of mitogen-activated protein kinases (MAPKs) in the spinal cord that are known to contribute to neuronal hyperexcitability, including c-Jun N-terminal kinase (JNK), p44/p42 extracellular signaling-regulated kinase (ERK), and p38. These findings demonstrate that central sensitization contributes to pain in SCD.

Environmental determinants of severity in sickle cell disease

Sickle cell disease causes acute and chronic illness, and median life expectancy is reduced by at least 30 years in all countries, with greater reductions in low-income countries. There is a wide spectrum of severity, with some patients having no symptoms and others suffering frequent, life-changing complications. Much of this variability is unexplained, despite increasingly sophisticated genetic studies. Environmental factors, including climate, air quality, socio-economics, exercise and infection, are likely to be important, as demonstrated by the stark differences in outcomes between patients in Africa and USA/Europe. The effects of weather vary with geography, although most studies show that exposure to cold or wind increases hospital attendance with acute pain. Most of the different air pollutants are closely intercorrelated, and increasing overall levels seem to correlate with increased hospital attendance, although higher concentrations of atmospheric carbon monoxide may offer some benefit for patients with sickle cell disease. Exercise causes some adverse physiological changes, although this may be off-set by improvements in cardiovascular health. Most sickle cell disease patients live in low-income countries and socioeconomic factors are undoubtedly important, but little studied beyond documenting that sickle cell disease is associated with decreases in some measures of social status. Infections cause many of the differences in outcomes seen across the world, but again these effects are relatively poorly understood. All the above factors are likely to account for much of the pathology and variability of sickle cell disease, and large prospective studies are needed to understand these effects better.

Environmental influences on daily emergency admissions in sickle-cell disease patients

Previous reports have suggested a role for weather conditions and air pollution on the variability of sickle cell disease (SCD) severity, but large-scale comprehensive epidemiological studies are lacking. In order to evaluate the influence of air pollution and climatic factors on emergency hospital admissions (EHA) in SCD patients, we conducted an 8-year observational retrospective study in 22 French university hospitals in Paris conurbation, using distributed lag non-linear models, a methodology able to flexibly describe simultaneously non-linear and delayed associations, with a multivariable approach. During the 2922 days of the study, there were 17,710 EHA, with a mean daily number of 6.1 ± 2.8. Most environmental factors were significantly correlated to each other. The risk of EHA was significantly associated with higher values of nitrogen dioxide, atmospheric particulate matters, and daily mean wind speed; and with lower values of carbon monoxide, ozone, sulfur dioxide, daily temperature (minimal, maximal, mean, and range), day-to-day mean temperature change, daily bright sunshine, and occurrence of storm. There was a lag effect for 12 of 15 environmental factors influencing hospitalization rate. Multivariate analysis identified carbon monoxide, day-to-day temperature change, and mean wind speed, along with calendar factors (weekend, summer season, and year) as independent factors associated with EHA. In conclusion, most weather conditions and air pollutants assessed were correlated to each other and influenced the rate of EHA in SCD patients. In multivariate analysis, lower carbon monoxide concentrations, day-to-day mean temperature drop and higher wind speed were associated with increased risk of EHA.

Climatic and geographic temporal patterns of pain in the Multicenter Study of Hydroxyurea

No multi-site comparisons have tested whether seasonally cold temperature or climate exacerbate pain intensity in sickle cell disease (SCD). We examined seasonal SCD pain intensity and frequency patterns and compared them with concurrent climate conditions (temperature and barometric pressure) and geography of patient residence in the Multicenter Study of Hydroxyurea (MSH). We conducted a time series analysis of the monthly average daily pain intensity (0-9 scale) and pain frequency of the 299 MSH patients from December 1991 to December 1994. We used both an unobserved component model (UCM) and a nonparametric local regression (LOESS) to probe for a cycle and/or trend associated with the time series. We also examined base mixed regression models of season, monthly average temperature and barometric pressure, and geographic region as stand-alone predictors of pain intensity and frequency. Expanded models included additional predictor variables. UCM and LOESS analyses showed a cyclic pattern of pain intensity and frequency with peaks in late Fall/early Winter and troughs in Spring. Base regression models showed colder seasons were significantly associated with greater pain intensity (p = .0035) but not frequency (p = .07); higher monthly temperatures were significantly associated with both lower pain intensity and pain frequency, but higher monthly barometric pressures were significantly associated with greater pain intensity and frequency (all p's < .0001); and northern sites had nonsignificantly higher pain intensity (p = .40) and frequency (p = .07) than southern sites. This pattern of results did not change in expanded models including other predictors. Our results suggest that seasonably colder temperatures exacerbate sickle cell-related pain, but low barometric pressure does not, and geographic region of residence is not significantly related to pain in this sample.

Association between wind speed and the occurrence of sickle cell acute painful episodes: results of a case-crossover study

The role of the weather as a trigger of sickle cell acute painful episodes has long been debated. To more accurately describe the role of the weather as a trigger of painful events, we conducted a case-crossover study of the association between local weather conditions and the occurrence of painful episodes. From the Cooperative Study of Sickle Cell Disease, we identified 813 patients with sickle cell anaemia who had 3570 acute painful episodes. We found an association between wind speed and the onset of pain, specifically wind speed during the 24-h period preceding the onset of pain. Analysing wind speed as a categorical trait, showed a 13% increase (95% confidence interval: 3%, 24%) in odds of pain, when comparing the high wind speed to lower wind speed (P = 0.007). In addition, the association between wind speed and painful episodes was found to be stronger among men, particularly those in the warmer climate regions of the United States. These results are in agreement with another study that found an association between wind speed and hospital visits for pain in the United Kingdom, and lends support to physiological and clinical studies that have suggested that skin cooling is associated with sickle vasoocclusion and perhaps pain.

Windy weather and low humidity are associated with an increased number of hospital admissions for acute pain and sickle cell disease in an urban environment with a maritime temperate climate

Sickle cell disease (SCD) is characterised by intermittent episodes of acute severe pain, related to vaso-occlusion. Environmental factors are thought to play an important role, and studies in tropical countries have suggested that cold and rainy seasons are associated with increased episodes of acute pain. We have studied retrospectively the number of admissions with acute pain and SCD to King's College Hospital, London, together with daily meteorological records collected locally. Data from 1400 d and 1047 separate admissions were analysed. Increased admissions were significantly associated with increased wind speed and low humidity, but showed no relationship to temperature, rainfall or barometric pressure. The strongest effect was for (maximum wind speed)/humidity, with 464 admissions on days in the lowest two quartiles of this parameter and 582 in the highest quartiles. The effect of high wind and low humidity is likely to be related to skin cooling.

Patient perceptions of crisis pain management in sickle cell disease: a cross-cultural study

Sickle cell disease has a variety of signs and symptoms, the most common being painful vaso-occlusive crises. Due to the severity of the pain, narcotic analgesia is described in the literature as the drug of choice for pain relief. The UK, in line with many other countries, uses narcotic analgesia in crisis management. In Jamaica, however, mild analgesia is the usual drug of choice for the patient in crisis. This difference in management approaches between the two countries was seen as an area for exploration to determine the factors which may reflect the nursing strategies used. This paper describes a cross-cultural survey of patients' perceptions of the painful crises and their management within the home and healthcare settings in Jamaica (West Indies) and Birmingham (UK).

The results of the study show many areas of similarities, particularly in relation to the causes of the crises, home management and in-patient admissions. However, there were significant differences in crisis length and the in-patient management of crises. The study highlighted areas of crisis management which must be improved in the UK if patients are to receive optimum care from primary care and hospital nurses, as well as from general practitioners.

Day-care management of sickle cell painful crisis in Jamaica: a model applicable elsewhere?

In the U.K. and the U.S.A., painful crises account for 80-90% of sickle-related hospital admissions, with average durations of 5-11 d. In Jamaica, many severe painful crises are managed in a day-care centre. Patients (n=1160) with homozygous sickle cell (SS) disease aged 18 years and over were registered with the clinic during a 1-year study period. Of these, 216 patients with 476 painful crises attended the day-care facility for a total of 686 d. Most patients (119 or 55.1%) had single crises and for most crises (338 or 71%), patients attended for only 1 d, when they were given bed rest, assurance, rehydration and analgesia. Patients with complicated painful crises were usually referred for admission after initial pain relief and the rest were monitored during the day. In the evening they were given the option of hospital admission or allowed home with oral analgesia. Hospital admission for complicated painful crises or inadequate pain relief occurred in 42 (8.8%) crises and home management in 434 (91.2%) crises. Of 186 patients initially selecting home management, 20% returned for further day-care and five (2.7%) died during subsequent admission for that painful crisis, one without other known complications, two with acute chest syndrome (one associated with Salmonella septicaemia), another with Salmonella septicaemia, and one with dengue haemorrhagic fever. With suitable oral analgesia, adequate education and support, the majority of severe painful crises in SS disease in Jamaica have been managed on an outpatient basis. This model of patient care may merit assessment in other communities where painful crises are a common clinical problem.

A comparative study in subjects with homozygous sickle cell disease and in normal subjects of responses evoked in forearm vasculature by mild, indirect cooling

We have studied responses evoked in the forearm vasculature of twelve subjects with homozygous sickle cell disease (SS) and in eight dark-skinned controls of West Indian ancestry (AA) by mild cooling of the contralateral hand in water at 16 degrees C for 2 min; this stimulus was repeated six times at randomized time intervals. Total forearm blood flow was measured by venous occlusion plethysmography, cutaneous red cell flux was monitored by a laser Doppler flowmeter and arterial pressure was recorded by semi-automatic sphygmomanometry. Of the AA subjects, three showed a decrease in total forearm vascular resistance (FVR, of -10%) in response to the first immersion and this reversed to an increase in FVR (+7%) by the sixth immersion. The remaining five showed an increase in FVR (+65%) which persisted until the sixth immersion (26%). By contrast, all SS subjects showed an increase in FVR (+32%) which persisted to the sixth stimulus (+27%). Further, on a scale of discomfort of 0-10, none of the AA subjects rated the cool stimulus higher than 0, whereas SS subjects gave a rating of 7 for the first stimulus which decreased to 5 by the sixth stimulus. Both AA and SS subjects showed an increase in arterial pressure and a tendency towards vasoconstriction in forearm skin. We propose that, as in Caucasian AA subjects, dark-skinned AA subjects showed a primary reflex vasoconstriction in forearm muscle in response to mild, indirect cooling which was overcome in some individuals by muscle vasodilation of the alerting response that is evoked by novel or noxious stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

Sickle cell disease in North London

We have examined our experience of sickle cell disease in the London Borough of Haringey over the past 20 years. There are currently (1986) 145 patients on the Haringey Sickle Cell Register and when comparison is made with other centres, admission for painful crises in Hb SS disease is more frequent than in Jamaica, but the acute chest syndrome appears to be less common in the United Kingdom than in Jamaica. Splenomegaly is less frequent in Hb SC patients in this country and there is also a lower incidence of leg ulceration in both Hb SS and Hb SC disease in the United Kingdom than in Jamaica. The incidence of alloimmunization among transfused sickle cell disease individuals in Haringey is 21%, the most frequently encountered antibodies being anti-E and anti-Kell. All pregnant patients with sickle cell disease were managed with regular blood transfusion throughout pregnancy starting at 12 weeks of gestation. There were no fetal or maternal mortalities, although three babies born were 'small for dates' despite uneventful antenatal courses and adequate Hb A levels being achieved in the mother. Examination of the effect of seasonal variation on the incidence of hospital admissions for painful crises reveals no significant clustering of cases in a particular month or season of the year.

Non relationship of climatologic factors and painful sickle cell anemia crisis

Conflicting results have arisen from studies concerning the correlation (if any) between climatological changes and the frequency of painful episodes in the sickle cell population. During a 13 month period records of 71 patients with hemoglobin genotypes SS or SC were reviewed. Data analysis failed to reveal an association between the frequency of painful sickle cell crisis and a number of weather and environmental variables. We were unable to demonstrate relationships between the climatologic factors of temperature, humidity, carbon monoxide level and precipitation in the frequency of 362 pain crises in 71 sickle cell patients during a 13 month period.

Observations on the natural history of dactylitis in homozygous sickle cell disease

The incidence of the hand-foot syndrome (dactylitis) has been studied in a group of 233 children with homozygous sickle cell (SS) disease followed prospectively from birth. Dactylitis affected 45% of the children by the age of 2 years, with most cases occurring before this age. Episodes were significantly more common during colder months of the year, similar to the seasonal relationship previously noted in painful crises. Comparison of hematologic indices at age 6 months in patients with and without development of dactylitis indicated a lower fetal hemoglobin and higher reticulocyte counts in affected patients. The occurrence of dactylitis in combination with low fetal hemoglobin may serve to identify high-risk patients with SS disease.

Relationship between meteorological changes and occurrence of painful sickle cell crises in Kuwait

In a retrospective study of 282 hospital admissions for sickle cell anaemia, a definite relationship was found between the occurrence of painful crises and seasonal changes in Kuwait. The findings are discussed in relation to the literature.

Climate and painful crisis of sickle-cell disease in Jamaica

In a 10-year retrospective study a close correlation was found between low temperatures and hospital admissions for severe painful crises of sickle-cell disease.