Meningococcal disease: a comparison of eight severity scores in 125 children

Invited review: Neisseria meningitidis lipopolysaccharides in human pathology

Neisseria meningitidis causes meningitis, fulminant septicemia or mild meningococcemia attacking mainly children and young adults. Lipopolysaccharides (LPS) consist of a symmetrical hexa-acyl lipid A and a short oligosaccharide chain and are classified in 11 immunotypes. Lipid A is the primary toxic component of N. meningitidis . LPS levels in plasma and cerebrospinal fluid as determined by Limulus amebocyte lysate (LAL) assay are quantitatively closely associated with inflammatory mediators, clinical symptoms, and outcome. Patients with persistent septic shock, multiple organ failure, and severe coagulopathy reveal extraordinarily high levels of LPS in plasma. The cytokine production is compartmentalized to either the circulation or to the subarachnoid space. Mortality related to shock increases from 0% to > 80% with a 10-fold increase of plasma LPS from 10 to 100 endotoxin units/ml. Hemorrhagic skin lesions and thrombosis are caused by up-regulation of tissue factor which induces coagulation, and by inhibition of fibrinolysis by plasminogen activator inhibitor 1 (PAI-1). Effective antibiotic treatment results in a rapid decline of plasma LPS (half-life 1—3 h) and cytokines, and reduced generation of thrombin, and PAI-1. Early antibiotic treatment is mandatory. Three intervention trials to block lipid A have not significantly reduced the mortality of meningococcal septicemia.

Supporting meningitis diagnosis amongst infants and children through the use of fuzzy cognitive mapping

Background

Meningitis is characterized by an inflammation of the meninges, or the membranes surrounding the brain and spinal cord. Early diagnosis and treatment is crucial for a positive outcome, yet identifying meningitis is a complex process involving an array of signs and symptoms and multiple causal factors which require novel solutions to support clinical decision-making. In this work, we explore the potential of fuzzy cognitive map to assist in the modeling of meningitis, as a support tool for physicians in the accurate diagnosis and treatment of the condition.

Methods

Fuzzy cognitive mapping (FCM) is a method for analysing and depicting human perception of a given system. FCM facilitates the development of a conceptual model which is not limited by exact values and measurements and thus is well suited to representing relatively unstructured knowledge and associations expressed in imprecise terms. A team of doctors (physicians), comprising four paediatricians, was formed to define the multifarious signs and symptoms associated with meningitis and to identify risk factors integral to its causality, as indicators used by clinicians to identify the presence or absence of meningitis in patients. The FCM model, consisting of 20 concept nodes, has been designed by the team of paediatricians in collaborative dialogue with the research team.

Results

The paediatricians were supplied with a form containing various input parameters to be completed at the time of diagnosing meningitis among infants and children. The paediatricians provided information on a total of 56 patient cases amongst children whose age ranged from 2 months to 7 years. The physicians’ decision to diagnose meningitis was available for each individual case which was used as the outcome measure for evaluating the model. The FCM was trained using 40 cases with an accuracy of 95%, and later 16 test cases were used to analyze the accuracy and reliability of the model. The system produced the results with sensitivity of 83.3% and specificity of 80%.

Conclusions

This work suggests that the application and development of a knowledge based system, using the formalization of FCMs for understanding the symptoms and causes of meningitis in children and infants, can provide a reliable front-end decision-making tool to better assist physicians.

Age-dependent association of human mannose-binding lectin mutations with susceptibility to invasive meningococcal disease in childhood

BACKGROUND

Mannose-binding lectin (MBL) is an important factor of the innate immune system, and MBL-initiated complement activation is an important early defense mechanism against various bacterial infections, including invasive meningococcal disease.

METHODS

In a pediatric cohort (ages 2-215 months) with invasive meningococcal disease, we investigated the overall and age-stratified frequency of 3 MBL exon 1 variations (C154T, G161A, G170A), previously shown to result in markedly decreased MBL plasma concentrations, by allele specific fluorescent hybridization probe real-time PCR assays and direct sequencing. Healthy age-matched volunteers with the same ethnic background and no history of meningococcal disease served as a control group.

RESULTS

The overall frequency of a MBL exon 1 variant genotype was significantly higher in patients than in controls (31.8% vs. 8.2%, P < 0.001). In the patient group with disease onset less than 24 months of age, the prevalence of MBL structural variant genotype was further increased (39.3%; P < 0.001) and most pronounced in children with disease onset less than 12 months of age (57.1%; P < 0.001) when compared with healthy controls. Analysis of clinical severity and outcome revealed no significant difference between patients with wild-type and mutant alleles.

CONCLUSIONS

Our data suggest that MBL exon 1 structural variants are significantly associated with susceptibility to childhood meningococcal disease in an age-dependent manner.

Elevated procalcitonin as a diagnostic marker in meningococcal disease

Patients with meningococcal disease who seek medical attention can create a diagnostic dilemma for clinicians due to the nonspecific nature of the disease's presentation. This study assesses the diagnostic accuracy of procalcitonin levels in the setting of meningococcal disease. Two emergency department cohorts (A and B) were studied between 2002 and 2005, during the current epidemic of serogroup B meningococcal disease in New Zealand. Cohort A consisted of 171 patients, all with confirmed meningococcal disease (84 children, 87 adults). Cohort B consisted of a large (n=1,524) consecutively recruited population of febrile patients who presented to the emergency department, 28 of whom had confirmed meningococcal disease. Within the meningococcal disease cohort (cohort A), the geometric mean procalcitonin level was 9.9 ng/ml, with levels being higher in children than in adults (21.6 vs. 4.6 ng/ml, p=0.01). The overall sensitivity of elevated procalcitonin, using a cutoff of 2.0 ng/ml in children and 0.5 ng/ml in adults, was 0.93 (95%CI: 0.88-0.96). Despite the higher cutoff level for paediatric patients, a trend towards greater sensitivity existed in children (0.96 vs. 0.90; p=0.08). Elevated procalcitonin was correlated with whole blood meningococcal load (r=0.50) and Glasgow Meningococcal Sepsis Prognostic Score (r=0.40). Within the cohort of patients who were febrile on presentation (cohort B), the specificity of elevated procalcitonin in meningococcal disease was 0.85 (95% CI: 0.83-0.87), the positive and negative likelihood ratios were 6.1 and 0.08, respectively, and the sensitivity of elevated procalcitonin (0.93; 95% CI: 0.76-0.99) was corroborated. Measurement of procalcitonin is a useful tool in patients with nonspecific febrile illnesses when the possibility of meningococcal disease is present. The diagnostic accuracy surpasses that of current early laboratory markers, allowing results to be used to guide decisions about patient management.

Malaria and fluids – balancing acts

Severe malaria has many manifestations, of which coma and lactic acidosis are the best independent predictors of a fatal outcome. Most deaths from malaria occur within the first 24 h of admission, despite appropriate antimalarial chemotherapy. Adjunctive therapy for severe malaria has been seen as a way to improve survival by 'buying time' until antimalarials can act. Several adjunctive therapies have undergone clinical trials in the past 25 years but all of these trials showed worsened outcome or no benefit to patients receiving adjuncts compared with those receiving placebo. Although metabolic acidosis occurs in both hypovolaemia and malaria, the contribution of the former to the pathophysiology of severe malaria is unclear. I suggest that lactic acidosis due to malaria can be explained primarily by factors that are independent of volume depletion. Lactic acidosis in malaria can be treated safely with dichloroacetate. This intervention could prove useful as an adjunctive therapy aimed at reducing mortality rates in severe malaria.

Assessment of adrenal function in the initial phase of meningococcal disease

OBJECTIVE

To determine the status of the hypothalamic-pituitary-adrenal axis in children who had meningococcal disease and were admitted to 2 regional pediatric intensive care units.

METHODS

Sixty-five children (34 boys; median age: 2.5 years; range: 0.2-15 years) had cortisol and adrenocorticotropic hormone (ACTH) levels measured on admission, then at 8 AM and 8 PM during the next 48 hours. At 48 hours, a low-dose short Synacthen test (LDST) (500 ng of 1-24 corticotropin/m2) was performed in 42 patients (19 boys). Normal ranges for 8 AM cortisol and ACTH levels in unstressed children were 140 to 500 nmol/L and 2 to 11.3 pmol/L, respectively. Adrenal insufficiency (AI) was defined as a peak cortisol <500 nmol/L on the LDST or an 8 AM cortisol value <140 nmol/L.

RESULTS

Five (7.7%) of the 65 children died, including 1 with primary AI. Cortisol levels were elevated on admission (median: 1122 mmol/L; range: 65-2110 nmol/L) with 81% of values more than the 8 AM normal range. The median ACTH level on admission was within the 8 AM normal range, but 40% of values were more than the 8 AM normal range. However, 7% and 8% of cortisol and ACTH values, respectively, were less than the normal range. Both cortisol and ACTH levels fell thereafter and showed no diurnal variation during the 48-hour profile. Six (14%) of the 42 failed the LDST. These patients had significantly lower mean 8 AM cortisol values than those with a normal peak value on the LDST. Five additional patients who did not have the LDST had 8 AM cortisol values <140 nmol/L. In the diagnosis of AI, the sensitivity of the 8 AM mean cortisol value at a cutoff of 400 nmol/L, judged against the LDST, was 83%; the specificity was 81%.

CONCLUSIONS

During the initial phase of meningococcal disease, raised cortisol and ACTH levels indicate an appropriate stress response within the hypothalamic-pituitary-adrenal axis. However, a substantial subpopulation (11 [16.9%] of 65) has evidence of adrenal dysfunction during this period. Morning cortisol values in the initial phase of meningococcal disease could be used as a potential early index of AI.

Antioxidant protection against iron in children with meningococcal sepsis

OBJECTIVE

To assess antioxidant protection against iron-catalyzed reactive oxygen species in meningococcal sepsis and to establish whether severity of illness is related to deficiencies in these antioxidant systems.

DESIGN

Prospective, controlled study.

SETTING

Pediatric intensive care unit of a postgraduate teaching hospital.

PATIENTS

Twenty children aged 6 months to 15 yrs (median, 5 yrs) with meningococcal septic shock were studied. Paired convalescent samples taken 8-10 wks after discharge were available in nine children.

INTERVENTIONS

Routine management for meningococcal sepsis.

MEASUREMENTS AND MAIN RESULTS

Patients were classified for disease severity using the Glasgow Meningococcal Septicaemia Prognostic Score. Paired acute and convalescent samples were compared. Transferrin level (1.77 +/- 0.08 g/L) and total iron-binding capacity (46.2 +/- 2.0 microM) were significantly decreased in acute patients compared with paired convalescent samples (2.85 +/- 0.10 g/L and 74.4 +/- 2.5 microM, respectively; p <.0001). The iron saturation of transferrin was significantly increased in acute disease (36.9% +/- 2.5%) compared with convalescence (18.8% +/- 1.5%; p =.0003). Iron-binding antioxidant protection was not significantly different in acute (81.4% +/- 1.7%) and paired convalescent samples (85.6% +/- 2.5%; p =.54). However, patients with more severe meningococcal septicemia (GMSPS, >10; n = 12) had significantly diminished protection (77.5% +/- 2.4%) compared with less severe disease (87.1% +/- 1.6%; p =.0028), and there was a significant correlation between disease severity and iron-binding antioxidant protection (R =.48; p =.00067) in acute disease. Paired ceruloplasmin levels were available in six patients and were decreased in acute disease (0.29 +/- 0.02 g/L) compared with convalescence (0.40 +/- 0.04 g/L), although not statistically significant (p =.076). However, there was a significant correlation between plasma ceruloplasmin and disease severity (Pearson product moment correlation, p =.038) in the acute patients. Iron-oxidizing antioxidant assays were performed in four paired samples and were diminished in acute patients (53.3 +/- 4.4%) compared with convalescence (67.8 +/- 3.2%; p =.015). Acute samples demonstrated a significant relationship between iron-oxidizing antioxidant protection and both disease severity (r =.30; p =.012) and plasma ceruloplasmin levels (r =.48; p =.00067).

CONCLUSIONS

Children with meningococcal septicemia exhibit abnormal plasma iron chemistry and decreased protection against iron-catalyzed oxidative damage. Such deficiencies correlate with disease severity.

Meningococcal disease: how to prevent and how to manage

Meningococcal disease is a significant problem in the paediatric population. The diagnosis of meningococcal disease can be problematic and progression of the disease can rapidly lead to a life-threatening illness. Despite the success of antibiotic treatment, mortality rates remain high. The development of protein-polysaccharide conjugate vaccines has significantly improved the success of vaccination in reducing the incidence of meningococcal disease. However, a comprehensive vaccine conferring protection against disease-associated serogroups remains elusive. The aim of this review is to highlight recent significant improvements in the prevention and management of meningococcal disease.

Reduction in case fatality rate from meningococcal disease associated with improved healthcare delivery

BACKGROUND AND AIMS

The case fatality rate from meningococcal disease (MD) has remained relatively unchanged in the post antibiotic era, with 20-50% of patients who develop shock still dying. In 1992 a new paediatric intensive care unit (PICU) specialising in MD was opened. Educational information was disseminated to local hospitals, and a specialist transport service was established which delivered mobile intensive care. The influence of these changes on mortality of children with MD was investigated.

METHODS

A total of 331 consecutive children with meningococcal disease admitted to the PICU between 1992 and 1997 were studied. Severity of the disease on admission was assessed using the paediatric risk of mortality (PRISM) score. Logistic regression analysis was used to correct for clinical severity, age, and sex; death was the outcome, and year of admission, a temporal trend variable, was the primary exposure.

RESULTS

The case fatality rate fell year on year (from 23% in 1992/93 to 2% in 1997) despite disease severity remaining largely unchanged. After adjustment for age, sex, and disease severity, the overall estimate for improvement in the odds of death was 59% per year (odds ratio for the yearly trend 0.41).

CONCLUSIONS

A significant improvement in outcome for children admitted with MD to a PICU has occurred in association with improvements in initial management of patients with MD at referring hospitals, use of a mobile intensive care service, and centralisation of care in a specialist unit.

Mortality in severe meningococcal disease

AIM

To evaluate mortality of critically ill children admitted with meningococcal disease.

METHODS

Prospective study of all children admitted to a regional paediatric intensive care unit (PICU) between January 1995 and March 1998 with meningococcal disease. Outcome measures were actual overall mortality, predicted mortality (by PRISM), and standardised mortality ratio.

RESULTS

A total of 123 children were admitted with meningococcal disease. There was an overall PICU mortality of 11 children (8.9%). The total mortality predicted by PRISM was 24.9. The standardised mortality ratio (SMR) was 0.44. Results were compared with those from four previously published meningococcal PICU studies (USA, Australia, UK, Netherlands) in which PRISM scores were calculated. The overall PICU mortality and SMR were lower than those in the previously published studies.

CONCLUSION

Compared with older studies and calibrating for disease severity, this study found a decrease in the mortality of critically ill children with meningococcal disease.

Can generic scores (Pediatric Risk of Mortality and Pediatric Index of Mortality) replace specific scores in predicting the outcome of presumed meningococcal septic shock in children?

OBJECTIVE

To compare, in children with septic shock and purpura, the accuracy in predicting death of two specific scores (the MenOPP bedside clinical [MOC] score of Gedde Dahl and the score of Groupe Francophone de Réanimation Pédiatrique [GFRP]), the C-reactive protein (CRP) level, and the two pediatric generic scores (the Pediatric Risk of Mortality [PRISM] and Pediatric Index of Mortality [PIM] scores).

DESIGN

Prospective, population-based study with analysis of previous comparative studies.

SETTING

A 14-bed pediatric intensive care unit in a university hospital.

PATIENTS

All children admitted consecutively to the pediatric intensive care unit with septic shock and purpura (n = 58, with 16 deaths [27.6%]) from January 1993 to May 2000.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The MOC and GFRP scores and the CRP level were prospectively determined at admission. The PRISM score was prospectively calculated within 24 hrs of admission or at the time of death, and the PIM score was calculated retrospectively between 1993 and 1997 and then prospectively from admission data. The nonparametric estimate of the area under the receiver operating characteristic curves (AUC) was calculated from the raw data using the Wilcoxon-Mann-Whitney two-sample statistic, and the standard error of the AUCs was calculated with DeLong's method. All the scores had an AUC >0.80, the PRISM probability of death having the best one (0.96 +/- 0.02). The PRISM value, which is easier to calculate, had an AUC of 0.95 +/- 0.02. The PRISM score performed significantly better than the PIM score (AUC, 0.83 +/- 0.06; p <.01) and the CRP level (AUC, 0.80 +/- 0.06; p <.01); however, there was no significant difference between the MOC (AUC, 0.91 +/- 0.04) and GFRP scores (AUC, 0.87 +/- 0.05). Analyzing literature and calculating AUCs from original data of previous studies, we observed that the superiority of the PRISM score had never been demonstrated in meningococcal diseases.

CONCLUSIONS

The PRISM score performed better than the PIM score, and was not surpassed by specific scores. Thus, we propose its use for outcome prediction in children with septic shock and purpura. However, if the PRISM score is to be used as inclusion criterion for clinical trials, it should be evaluated within a few hours after admission.

Comparison of the performance of two general and three specific scoring systems for meningococcal septic shock in children

OBJECTIVE

To evaluate the performance at admission to the pediatric intensive care unit (PICU) of five severity scores, two general (the Pediatric Risk of Mortality [PRISM] II and III scores) and three specific for meningococcal septic shock (Leclerc, Glasgow Meningococcal Septicemia Prognostic Score [GMSPS], and Gedde-Dahl's MOC score) in children with this condition.

DESIGN

Multicenter, retrospective, cohort study.

SETTING

The PICUs from four tertiary centers.

PATIENTS

Patients were 192 children ranging in age from 1 month to 14 yrs consecutively admitted to the participating PICUs during a period of 12 yrs and 6 months (January 1983 to June 1995), who were diagnosed with presumed or confirmed meningococcal septic shock. Patients with a length of stay <2 hrs were excluded from the study.

INTERVENTIONS

Clinical and laboratory data gathered during the first 2 hrs after admission were used to compute the scoring systems tested.

MEASUREMENTS AND MAIN RESULTS

There were 66 deaths (34%). Neisseria meningitidis was cultured from 142 (74%) children. GMSPS and PRISM II provided the best discriminative capability, as measured by the area under the receiver operating characteristic curve (SEM): 0.816 (0.036) and 0.803 (0.041), respectively. The other three scores gave lower receiver operating characteristic areas: PRISM III = 0.777 (0.043), MOC = 0.775 (0.037), and Leclerc = 0.661 (0.045). There was a statistically significant difference between the areas under the receiver operating characteristic curve of GMSPS and Leclerc (p < .01) but not between the GMSPS and the remaining three scores. All five scores presented good calibration with no significant differences between observed and predicted mortality (Hosmer-Lemeshow goodness-of-fit test).

CONCLUSIONS

The specific GMSPS and the general pediatric severity system PRISM II performed better than the other three scores, being appropriate tools to assess severity of illness at admission to the PICU in children with presumed meningococcal septic shock.

Update on meningococcal disease with emphasis on pathogenesis and clinical management

The only natural reservoir of Neisseria meningitidis is the human nasopharyngeal mucosa. Depending on age, climate, country, socioeconomic status, and other factors, approximately 10% of the human population harbors meningococci in the nose. However, invasive disease is relatively rare, as it occurs only when the following conditions are fulfilled: (i) contact with a virulent strain, (ii) colonization by that strain, (iii) penetration of the bacterium through the mucosa, and (iv) survival and eventually outgrowth of the meningococcus in the bloodstream. When the meningococcus has reached the bloodstream and specific antibodies are absent, as is the case for young children or after introduction of a new strain in a population, the ultimate outgrowth depends on the efficacy of the innate immune response. Massive outgrowth leads within 12 h to fulminant meningococcal sepsis (FMS), characterized by high intravascular concentrations of endotoxin that set free high concentrations of proinflammatory mediators. These mediators belonging to the complement system, the contact system, the fibrinolytic system, and the cytokine system induce shock and diffuse intravascular coagulation. FMS can be fatal within 24 h, often before signs of meningitis have developed. In spite of the increasing possibilities for treatment in intensive care units, the mortality rate of FMS is still 30%. When the outgrowth of meningococci in the bloodstream is impeded, seeding of bacteria in the subarachnoidal compartment may lead to overt meningitis within 24 to 36 h. With appropriate antibiotics and good clinical surveillance, the mortality rate of this form of invasive disease is 1 to 2%. The overall mortality rate of meningococcal disease can only be reduced when patients without meningitis, i.e., those who may develop FMS, are recognized early. This means that the fundamental nature of the disease as a meningococcus septicemia deserves more attention.

Update on meningococcal disease with emphasis on pathogenesis and clinical management

The only natural reservoir of Neisseria meningitidis is the human nasopharyngeal mucosa. Depending on age, climate, country, socioeconomic status, and other factors, approximately 10% of the human population harbors meningococci in the nose. However, invasive disease is relatively rare, as it occurs only when the following conditions are fulfilled: (i) contact with a virulent strain, (ii) colonization by that strain, (iii) penetration of the bacterium through the mucosa, and (iv) survival and eventually outgrowth of the meningococcus in the bloodstream. When the meningococcus has reached the bloodstream and specific antibodies are absent, as is the case for young children or after introduction of a new strain in a population, the ultimate outgrowth depends on the efficacy of the innate immune response. Massive outgrowth leads within 12 h to fulminant meningococcal sepsis (FMS), characterized by high intravascular concentrations of endotoxin that set free high concentrations of proinflammatory mediators. These mediators belonging to the complement system, the contact system, the fibrinolytic system, and the cytokine system induce shock and diffuse intravascular coagulation. FMS can be fatal within 24 h, often before signs of meningitis have developed. In spite of the increasing possibilities for treatment in intensive care units, the mortality rate of FMS is still 30%. When the outgrowth of meningococci in the bloodstream is impeded, seeding of bacteria in the subarachnoidal compartment may lead to overt meningitis within 24 to 36 h. With appropriate antibiotics and good clinical surveillance, the mortality rate of this form of invasive disease is 1 to 2%. The overall mortality rate of meningococcal disease can only be reduced when patients without meningitis, i.e., those who may develop FMS, are recognized early. This means that the fundamental nature of the disease as a meningococcus septicemia deserves more attention.

Recognition, treatment and complications of meningococcal disease

Meningococcal disease remains a major cause of death in young children. A decrease in mortality requires recognition and treatment of the disease at a number of stages in the illness. Life-threatening meningococcal disease usually presents as septicaemia rather than meningitis. The cardinal feature of meningococcal septicaemia is the purpuric rash. Many parents recognise the rash and seek medical advice because of it. When primary care physicians recognise the rash, the administration of parenteral penicillin may decrease mortality. However, antibacterials are not given promptly if there is no rash or if the disease presents in an atypical form. In hospital, antibacterial therapy with a third-generation cephalosporin should be given. Disease severity needs to be assessed by a valid method, such as the Glasgow Meningococcal Septicaemia Prognostic Score (GMSPS). This can identify those patients who need intensive care and/or might benefit from new therapies. The 2 life-threatening complications are septic shock and meningoencephalitis with raised intracranial pressure. Despite numerous case reports of success with potential new treatments, none has been proven safe and/or effective by controlled trials. Although it is tempting to focus on new treatments, the early recognition of severe meningococcal disease by parents, primary care physicians and junior hospital doctors is equally, if not more, important as a potential means of decreasing mortality.

Endotoxin release and cytokine production in acute and chronic meningococcaemia

Chronic meningococcaemia is a relatively benign manifestation of meningococcal disease. Whether bacterial virulence factors are responsible for this benign course has not been studied. We compared the in vitro endotoxin-liberating ability and cytokine-inducing potential of 31 Neisseria meninigitidis isolates obtained from children with acute septic shock with that of nine isolates obtained from patients with chronic meningococcaemia and 12 isolates obtained from carriers with respiratory symptoms. The median endotoxin level released in vitro after 3 h of incubation was significantly higher for isolates causing septic shock compared with isolates from the other two groups (P=0.01 and 0.02, Mann-Whitney test). This was not explained by differences in bacterial growth rate in vitro. The median IL-6 levels in whole blood ex vivo after 4 h of incubation were also significantly lower for isolates causing chronic meningococcaemia (P=0.04, Mann-Whitney test). The endotoxin and cytokine levels measured on admission in the 31 children with acute meningococcal septic shock showed a 1000-fold variation. No relationship was established between the amount of endotoxin released by the causative microorganisms in vitro and the endotoxin or cytokine levels in the corresponding 31 children. These results suggest a diminished bacterial virulence for isolates causing chronic meningococcaemia. However, other factors than the endotoxin-releasing potential of the microorganism involved are responsible for the wide variation in endotoxin and therefore cytokine levels in patients with acute meningococcal septic shock.

A normal platelet count at admission in acute meningococcal disease does not exclude a fulminant course

OBJECTIVE

To determine the value of the platelet count at admission for the assessment of the severity of disease in acute meningococcal infections.

DESIGN

Retrospective and prospective, descriptive patient study.

SETTING

University Hospital Intensive Care Unit (ICU).

PATIENTS

All patients (n = 92) with acute meningococcal disease from 1985 to 1997, who arrived at the ICU within 12 h after hospital admission and had more than one platelet count during the first 12 h.

MEASUREMENTS AND RESULTS

After admission, platelets dropped in 95% of the patients. At admission, 2/41 (5%) of the non-hypotensive patients and 13/51 (25%) of the hypotensive patients had platelets fewer than 100 x 10(9)/l. During the following 12 h, these percentages increased to 15% and 71%, respectively. Fatalities had, at admission, a median platelet count of 111 x 10(9)/l (range, 19-302 x 10(9)/l), whereas the nadir, occurring at median 7.0 h (range, 1.3-12 h), was 31 x 10(9)/l (range, 12-67 x 10(9)/l). Plasma TNF, measured shortly after admission, correlated better with the platelet nadir (r = -0.65, p < 0.0001) than with the platelet count at admission. Similarly, serum lactate correlated better with the platelet nadir.

CONCLUSIONS

As platelets drop after admission, the use of the platelet count at admission for the assessment of the prognosis in acute meningococcal disease may be misleading. Frequently repeated platelet counts are a better tool for evaluating the severity of disease.