J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 4, Number 6, December 2012, pages 415-423

Etiology of Thrombocytosis in a General Medicine Population: Analysis of 801 Cases With Emphasis on Infectious Causes

**Table 1.** Pre-Existing Conditions^a
Pre-existing condition	Number of patients (n = 801)	Percentage (n = 801)
^aEach patient in the study could have multiple pre-existing conditions. Abbreviations: COPD = chronic obstructive pulmonary disease; HIV = human immunodeficiency virus.
Diabetes mellitus	243	30.3%
Malignancy	206	25.7%
Coronary artery disease	198	24.7%
COPD	126	15.7%
Alcoholism	121	15.1%
Chronic renal insufficiency	72	9.0%
Chronic liver disease	67	8.4%
Peripheral vascular disease	52	6.5%
Dementia	49	6.1%
Quadriplegia/paraplegia	30	3.7%
HIV	9	1.1%

Table 1. Pre-Existing Conditions^a

Pre-existing condition

Number of patients (n = 801)

Percentage (n = 801)

^aEach patient in the study could have multiple pre-existing conditions. Abbreviations: COPD = chronic obstructive pulmonary disease; HIV = human immunodeficiency virus.

Diabetes mellitus

243

30.3%

Malignancy

206

25.7%

Coronary artery disease

198

24.7%

COPD

126

15.7%

Alcoholism

121

15.1%

Chronic renal insufficiency

9.0%

Chronic liver disease

8.4%

Peripheral vascular disease

6.5%

Dementia

6.1%

Quadriplegia/paraplegia

3.7%

HIV

1.1%

**Table 2.** Etiology of Thrombocytosis
Etiology	Number of cases (n = 890)^a	Percentage of patients with each etiology (n = 801)^a
^aBecause some patients had multiple etiologies of thrombocytosis, the total number of cases exceeds the number of patients in the study, and percentages add up to greater than 100%; ^be.g., trauma, bone fracture, surgery; ^ce.g., rheumatoid arthritis, systemic lupus erythematosus; ^de.g., small-bowel obstruction, bile-duct obstruction, gastric perforation, spinal-cord compression, drug-induced skin rash, knee inflammation, pericarditis and over-correction of the bone marrow; ^ee.g., bacteremia without a source, intravascular-line infections, endocarditis, wound infections, parotitis, otitis media and externa, odontogenic infection and phlebitis. Abbreviations: MPD = myeloproliferative disorder.
Primary	42	5.2%
Essential thrombocythemia	22
Polycythemia vera	10
Chronic myelogenous leukemia	1
Unspecified MPD	9
Secondary, non-infectious	405	50.6%
Tissue damage^b	196
Malignancy	86
Iron-deficiency anemia	59
Chronic inflammatory disease^c	37
Drug related	26
Post-splenectomy	12
Other^d	23
Secondary, infectious	384	47.9%
Soft-tissue infection	143
Pulmonary infection	123
Gastrointestinal infection	83
Genitourinary infection	80
Osteomyelitis	31
Other^e	56
Indeterminate	59	7.4%

Table 2. Etiology of Thrombocytosis

Etiology

Number of cases (n = 890)^a

Percentage of patients with each etiology (n = 801)^a

^aBecause some patients had multiple etiologies of thrombocytosis, the total number of cases exceeds the number of patients in the study, and percentages add up to greater than 100%; ^be.g., trauma, bone fracture, surgery; ^ce.g., rheumatoid arthritis, systemic lupus erythematosus; ^de.g., small-bowel obstruction, bile-duct obstruction, gastric perforation, spinal-cord compression, drug-induced skin rash, knee inflammation, pericarditis and over-correction of the bone marrow; ^ee.g., bacteremia without a source, intravascular-line infections, endocarditis, wound infections, parotitis, otitis media and externa, odontogenic infection and phlebitis. Abbreviations: MPD = myeloproliferative disorder.

Primary

5.2%

Essential thrombocythemia

Polycythemia vera

Chronic myelogenous leukemia

Unspecified MPD

Secondary, non-infectious

405

50.6%

Tissue damage^b

196

Malignancy

Iron-deficiency anemia

Chronic inflammatory disease^c

Drug related

Post-splenectomy

Other^d

Secondary, infectious

384

47.9%

Soft-tissue infection

143

Pulmonary infection

123

Gastrointestinal infection

Genitourinary infection

Osteomyelitis

Other^e

Indeterminate

7.4%

**Table 3.** Incidence of Isolated Microorganisms
Microorganism	Number of cases
^ae.g., Acinetobacter, Actinomyces, Citrobacter, Corynebacterium, Haemophilus influenzae, Mycobacterium, Prevotella, Propionobacterium, Salmonella and Serratia.
Methicillin-resistant Staphylococcus aureus	63
Clostridium difficile	48
Enterococcus sp.	37
Pseudomonas sp.	36
Escherichia coli	35
Klebsiella sp.	23
Coagulase negative staphylococci (CONS)	22
Methicillin-sensitive Staphylococcus aureus (MSSA)	20
Beta-hemolytic streptococci	16
Other streptococci	16
Proteus sp.	11
Bacteriodes sp.	7
Candida sp.	7
Other^a	26

Table 3. Incidence of Isolated Microorganisms

Microorganism

Number of cases

^ae.g., Acinetobacter, Actinomyces, Citrobacter, Corynebacterium, Haemophilus influenzae, Mycobacterium, Prevotella, Propionobacterium, Salmonella and Serratia.

Methicillin-resistant Staphylococcus aureus

Clostridium difficile

Enterococcus sp.

Pseudomonas sp.

Escherichia coli

Klebsiella sp.

Coagulase negative staphylococci (CONS)

Methicillin-sensitive Staphylococcus aureus (MSSA)

Beta-hemolytic streptococci

Other streptococci

Proteus sp.

Bacteriodes sp.

Candida sp.

Other^a

**Table 4.** Features Significantly Associated With an Infectious Cause of Thrombocytosis by Univariate Analysis
Clinical or laboratory feature	Percentage of patients with an infectious cause of thrombocytosis among patients with or without the specified clinical or laboratory feature	P value for Chi-square analysis
^aFor example, 65.4% of inpatients had an infectious cause of thrombocytosis, whereas 23% of outpatients had an infectious cause of thrombocytosis. Abbreviations: C = Celsius; bpm = beats per minute; Hb = hemoglobin.
Clinical characteristics	With	Without
Inpatient status^a	65.4%	23.0%	< 0.0001
Quadriplegia/paraplegia	80.0%	46.6%	0.0003
Indwelling prosthesis	65.4%	30.1%	< 0.0001
Dementia	73.5%	46.3%	0.0002
Diabetes	56.4%	44.3%	0.0016
Physical exam findings	With	Without
Fever (temperature ≥ 38 °C)	91.4%	47.5%	< 0.0001
Tachycardia (heart rate > 100 bpm)	65.4%	44.9%	< 0.0001
Weight loss (> 4.55 kg in 3 months)	52.1%	40.6	0.0087
Laboratory features	With	Without
Albumin < 35 g/L (3.5 g/dL)	57.8%	20.6%	< 0.0001
Absolute neutrophil count > 8 × 10⁹/L	71.7%	37.6%	< 0.0001
White blood cell count > 10 × 10⁹/L	61.6%	33.1%	< 0.0001
Anemia (Hb < 120 g/L) (12 g/dL)	51.0%	42.9%	0.0282

Table 4. Features Significantly Associated With an Infectious Cause of Thrombocytosis by Univariate Analysis

Clinical or laboratory feature

Percentage of patients with an infectious cause of thrombocytosis among patients with or without the specified clinical or laboratory feature

P value for Chi-square analysis

^aFor example, 65.4% of inpatients had an infectious cause of thrombocytosis, whereas 23% of outpatients had an infectious cause of thrombocytosis. Abbreviations: C = Celsius; bpm = beats per minute; Hb = hemoglobin.

Clinical characteristics

With

Without

Inpatient status^a

65.4%

23.0%

< 0.0001

Quadriplegia/paraplegia

80.0%

46.6%

0.0003

Indwelling prosthesis

65.4%

30.1%

< 0.0001

Dementia

73.5%

46.3%

0.0002

Diabetes

56.4%

44.3%

0.0016

Physical exam findings

With

Without

Fever (temperature ≥ 38 °C)

91.4%

47.5%

< 0.0001

Tachycardia (heart rate > 100 bpm)

65.4%

44.9%

< 0.0001

Weight loss (> 4.55 kg in 3 months)

52.1%

40.6

0.0087

Laboratory features

With

Without

Albumin < 35 g/L (3.5 g/dL)

57.8%

20.6%

< 0.0001

Absolute neutrophil count > 8 × 10⁹/L

71.7%

37.6%

< 0.0001

White blood cell count > 10 × 10⁹/L

61.6%

33.1%

< 0.0001

Anemia (Hb < 120 g/L) (12 g/dL)

51.0%

42.9%

0.0282

**Table 5.** Multivariate Analysis^a: Features Which Increased the Likelihood of Having an Infectious Cause of Thrombocytosis Versus a Non-Infectious Cause
Clinical or laboratory feature	Odds ratio	95% Wald Confidence Limit
^aA stepwise logistic regression model was used for multivariate analysis; see text for details. C statistic = 0.783. Hosmer and Lemeshow goodness-of-fit statistic, P = 0.3149. Abbreviations: C = Celsius; bpm = beats per minute.
Fever (temperature ≥ 38 °C)	6.64	1.86 - 23.73
Inpatient status	5.04	3.51 - 7.25
Dementia	2.44	1.17 - 5.06
White blood cell count > 10 × 10⁹/L	2.13	1.52 - 2.99
Diabetes	1.67	1.16 - 2.39
Tachycardia (heart rate > 100 bpm)	1.66	1.08 - 2.54

Table 5. Multivariate Analysis^a: Features Which Increased the Likelihood of Having an Infectious Cause of Thrombocytosis Versus a Non-Infectious Cause

Clinical or laboratory feature

Odds ratio

95% Wald Confidence Limit

^aA stepwise logistic regression model was used for multivariate analysis; see text for details. C statistic = 0.783. Hosmer and Lemeshow goodness-of-fit statistic, P = 0.3149. Abbreviations: C = Celsius; bpm = beats per minute.

Fever (temperature ≥ 38 °C)

6.64

1.86 - 23.73

Inpatient status

5.04

3.51 - 7.25

Dementia

2.44

1.17 - 5.06

White blood cell count > 10 × 10⁹/L

2.13

1.52 - 2.99

Diabetes

1.67

1.16 - 2.39

Tachycardia (heart rate > 100 bpm)

1.66

1.08 - 2.54