Influence of geomagnetic disturbances on myocardial infarctions in women and men from Brazil

Influence of geomagnetic disturbances on myocardial infarctions in women and men from Brazil

Luiz Felipe C. Rezende1, Eurico R. De Paula1, Marcio T.A.H Muella2, Severino G. Dutra1, Reinaldo. R. Rosa1, Paulo H. N. Saldiva3, Jean P.H.B. Ometto1

National Institute for Space Research (INPE), Sao Jose dos Campos, Brazil

Universidade do Vale do Paraíba (UNIVAP), Sao Jose dos Campos, Brazil

University of São Paulo (USP), Sao Paulo, Brazil

Admissions and deaths for myocardial infarctions (MI)

The data (admissions and deaths) for myocardial infarctions (MI) were obtained from the Unified Health System (SUS) database in Brazil. These cases pertained to residents within São José dos Campos municipality (23° 10′ 44″ S, 45° 53′ 13″ W) in the state of São Paulo (population: currently around 737,000 inhabitants and 87 km far from the state capital: São Paulo). The SUS is a public healthcare system, and the coverage rate of the public health network in most municipalities in Brazil is around 70%, with the remaining 30% being served by the complementary healthcare network.

Health data (myocardial infarctions) were provided by City Hall of São José dos Campos, Secretary of Health.

The data comprise the period from January 1, 1998 to May 31, 2005 which almost entirely comprised. The selection of heart attack cases was based on the International Classification of Diseases (ICD), classifications: I21, I22.

Kp index

We used the Kp-index to quantify or categorize the intensity and fluctuations of the geomagnetic field (GMF) or Geomagnetic Disturbances (GMDs). The Kp-index is the global geomagnetic activity index that is based on 3-hour measurements from ground-based magnetometers around the world. Each station is calibrated according to its latitude and yields a specific K-index, reflecting the geomagnetic activity recorded at the magnetometer’s location. The Kp-index ranges from 0 to 9, with 0 indicating minimal geomagnetic activity and 9 denoting severe geomagnetic activity. The data were obtained from the Kyoto website:

https://wdc.kugi.kyoto-u.ac.jp/kp/index.html

Kyoto data is transferred to Helmholtz Centre Potsdam and can be found at the link:https://www.gfz-potsdam.de/en/kp-index/

The data were converted from Coordinated Universal Time (UTC) to local time (-3 hours), and we have presented the classification of the Kp index into quiet, moderate, and strongly disturbed days based on the daily summation of Kp values (Table 1).

Table 1 Classification of days (quiet, moderate, and disturbed)

Rule

Classification

∑Kpdaily≤ 24

Quiet

∑Kpdaily> 24 and ∑kpdaily≤ 32

Moderate

∑Kpdaily> 32

Disturbed

We combined the Myocardial infarctions and Kp index data, generating the Supplementary Data 1 dataset.

Columns of dataset (Supplementary Data 1):

Day

Month

Year

Age

Sex (1 Male, 2 Female)

ICD (I21, I22)

STATUS (1 Discharge; 2 Death, 3 Transfer, 4 Permanent, and 5 Evasion)

KP (SUM) 

GEOMAGNETIC CONDITION (0 Quiet, 1 Moderate, 2 Disturbed)

Clustering

We use K-Means, an unsupervised clustering method using Weka 3.8.6 that is an open-source machine learning software issued under the GNU General Public License [39,40]. We chose to adopt 4 clusterings and 4 attributes: geomagnetic condition (discrete: quiet, moderate, or disturbed), Kp sum (numeric), sex(discrete: female or male) and age (numeric) and the centroids of the attributes were calculated using Euclidean distance.