Figure 1 shows the total number of eligible patients included in the ITS, the number of patients in April and May 2020 when the state of emergency was declared, and the number of patients during the same period in 2019. A total of 175,166 eligible patients were identified between April 2018 to August and August 2020. When the state of emergency was declared, there were 6,040 hospitalised patients in April and 6,444 in May. For the same period in 2019, 6,197 and 6,828 patients were admitted in April and May, respectively.
Table 1 shows the pre-hospital baseline characteristics of patients admitted in April and May 2019 and 2020. There was no difference between the COVID-19 and the pre-COVID-19 pandemic periods in any of the pre-hospital baseline variables.
Table 1
Baseline characteristics of patients with stroke
Variables | | Pre-COVID-19 period | COVID-19 period | | |
n | | 13,025 | | 12,484 | | SMD | P value |
Age, N, % | | | | | | 0.025 | 0.564 |
| 20–44 | 328 | (2.5) | 301 | (2.4) | | |
| 45–54 | 936 | (7.2) | 824 | (6.6) | | |
| 55–64 | 1,498 | (11.5) | 1,452 | (11.6) | | |
| 65–74 | 3,193 | (24.5) | 3,067 | (24.6) | | |
| 75–84 | 4,008 | (30.8) | 3,868 | (31.0) | | |
| 85 and over | 3,062 | (23.5) | 2,972 | (23.8) | | |
Sex (Female), N, % | | 5,711 | (43.8) | 5,482 | (43.9) | 0.001 | 0.926 |
BMI, N, % | | | | | | 0.044 | 0.032 |
| < 18.5 | 1,408 | (11.0) | 1,425 | (11.6) | | |
| 18.5–24.9 | 7,088 | (55.1) | 6,629 | (53.9) | | |
| 25–29 | 2,496 | (19.4) | 2,441 | (19.8) | | |
| 30–34 | 504 | (3.9) | 423 | (3.4) | | |
| 35 and over | 519 | (4.0) | 504 | (4.1) | | |
| NA | 838 | (6.5) | 879 | (7.1) | | |
CCI, N, % | | | | | | 0.025 | 0.27 |
| 0 | 11,196 | (86.0) | 10,774 | (86.3) | | |
| 1 | 1,585 | (12.2) | 1,458 | (11.7) | | |
| 2 | 209 | (1.6) | 226 | (1.8) | | |
| 3 | 35 | (0.3) | 26 | (0.2) | | |
Cerebral infarction, N, % | | 9,623 | (73.9) | 8,847 | (70.9) | 0.045 | < 0.001 |
Cerebral haemorrhage, N, % | | 2,768 | (21.3) | 2,915 | (23.3) | | |
Subarachnoid haemorrhage, N, % | | 634 | (4.9) | 722 | (5.8) | | |
Admission pathway, N, % | | | | | | 0.036 | 0.041 |
| Home | 11,581 | (88.9) | 11,195 | (89.7) | | |
| Facility | 1,028 | (7.9) | 956 | (7.7) | | |
| Transfer | 402 | (3.1) | 316 | (2.5) | | |
| Else | 14 | (0.1) | 17 | (0.1) | | |
Stroke of onset time, N, % | | | | | | 0.056 | < 0.001 |
| 3 days or less | 12,103 | (93.1) | 11,739 | (94.2) | | |
| 4–7 days | 544 | (4.2) | 472 | (3.8) | | |
| 8 days or more | 221 | (1.7) | 176 | (1.4) | | |
| Asymptomatic | 128 | (1.0) | 72 | (0.6) | | |
Ambulation, N, % | | 8,266 | (63.5) | 8,396 | (67.3) | 0.08 | < 0.001 |
BMI: body mass index; JCS: Japan Coma Scale; BI: Barthel Index; CCI: Charlson Comorbidity Index; SMD: standardised mean difference |
No significant and effective difference was found when comparing the COVID-19 with the pre-COVID-19 pandemic periods in each age group.
In each stroke category, there was a significant but the difference in effect size was not sufficient difference between the COVID-19 and the pre-COVID-19 pandemic periods (COVID-19 period (3 days or less, 4–7 days, 8 days or more, asymptomatic): 12,103, 544, 221, and 128, respectively vs pre-COVID-19 period (3 days or less, 4–7 days, 8 days or more, asymptomatic): 11,739, 472, 176, and 72, respectively; SMD = 0.08, P < 0.001)
In the category of stroke-to-onset days, there was a significant but the difference in effect size was not sufficient difference between the COVID-19 and the pre-COVID-19 pandemic periods (COVID-19 [CI, CH, SH]: 9,623, 2,768, and 634, respectively vs pre-COVID-19 periods (CI, CH, SH): 8,843, 2,915, and 722, respectively; SMD = 0.045, P < 0.001).
Table 2 shows the mean values of JCS, LOS, number of deaths, and number of deaths within 24 hours, mRS, and number of discharges by COVID-19 pandemic period for post-hospitalization variables. There was a significant effective difference in the JCS disorientation score between the COVID-19 and the pre-COVID-19 pandemic levels, and more patients were hospitalized with severe disorientation during the COVID-19 pandemic (COVID-19 (JCS0, JCS1, JCS2, JCS3): 5,362, 5,090, 1,368, and 1,205, respectively vs pre-COVID-19 periods (JCS0, JCS1, JCS2, JCS3): 4,334, 5,169, 1,448, and 1,533, respectively; SMD = 0.148, P < 0.001). Discharge mRS and mortality were s there was a significant but the difference in effect size was not sufficient difference during and before the COVID-19 pandemic, but there was a significant and effective difference in 24-hour mortality upon admission (COVID-19: 184 vs pre-COVID-19 periods: 518, SMD = 0.167, P < 0.001). There was also a significant and effective difference in the category of discharge destination, with more patients being transferred to other hospitals (COVID-19 (home, facility, hospital, others): 6,637, 747, 4,234, and 1,407, respectively vs pre-COVID-19 periods (home, facility, hospital, others): 5,744, 589, 4,560, and 1,591, respectively; SMD = 0.122, P < 0.001).
Table 2
The mean number of JCS, LOS, Fatalities, Fatalities in 24 h, mRS, and Discharge by COVID-19 pandemic period
Variables | | COVID-19 period | Pre-COVID-19 period | SMD | P value |
JCS, N, % | | | | | | 0.148 | < 0.001 |
| 0 | 5,362 | (41.2) | 4,334 | (34.7) | | |
| 1 | 5,090 | (39.1) | 5,169 | (41.4) | | |
| 2 | 1,368 | (10.5) | 1,448 | (11.6) | | |
| 3 | 1,205 | (9.3) | 1,533 | (12.3) | | |
LOS, Mean, SD | 15.33 | (7.6) | 15.06 | (7.6) | 0.036 | 0.004 |
Fatalities, N, % | | 1,403 | (10.8) | 1,586 | (12.7) | 0.06 | < 0.001 |
Fatalities in 24h, N, % | | 184 | (1.4) | 518 | (4.1) | 0.167 | < 0.001 |
mRS at discharge, N, % | | | | | | 0.004 | < 0.001 |
| 0 | 1,439 | (12.4) | 1,202 | (11.1) | | |
| 1 | 3,010 | (26.0) | 2,590 | (23.9) | | |
| 2 | 2,198 | (19.0) | 2,072 | (19.1) | | |
| 3 | 1,553 | (13.4) | 1,394 | (12.8) | | |
| 4 | 2,302 | (19.9) | 2,423 | (22.3) | | |
| 5 | 1,065 | (9.2) | 1,177 | (10.8) | | |
Discharge, N, % | | | | | | 0.122 | < 0.001 |
| Home | 6,637 | (51.0) | 5,744 | (46.0) | | |
| Facility | 747 | (5.7) | 589 | (4.7) | | |
| Hospital | 4,234 | (32.5) | 4,560 | (36.5) | | |
| other | 1,407 | (10.8) | 1,591 | (12.7) | | |
LOS: length of hospital stay; JCS: Japan Coma Scale; mRS: modified Ranking Scale |
Figures 2_1 to 2_3 and Table 3 show the results of the ITS for the number of stroke patients from April 2018 to August 2020. There was no significant change in the number of emergency stroke admissions adjusted for ITS between the COVID-19 and the pre-COVID-19 pandemic periods (risk ratio [RR] = 0.96, 95% confidence interval [95%CI]: 0.90–1.02, P = 0.159).
Table 3
Interrupted time series analysis for the number of stroke patients from April 2018 to August 2020
| RR | 2.50% | 97.5% | P value | |
Hospital admissions | 0.96 | 0.90 | 1.02 | 0.159 | |
JCS1 | 1.03 | 0.99 | 1.06 | 0.607 | |
JCS2 | 1.02 | 0.96 | 1.08 | 0.554 | |
JCS3 | 1.36 | 1.26 | 1.46 | < 0.001 | ** |
Deaths within 24 h | 2.80 | 2.44 | 3.22 | < 0.001 | *** |
Deaths except in 24 h | 0.97 | 0.90 | 1.03 | 0.287 | |
***: p < 0.001, ** : p < 0.01, * : p < 0.05. |
JCS: Japan Coma Scale; RR: risk ratio |
There was a significant difference in JCS levels only for JCS3, and impaired consciousness in emergency stroke patients was more severe during the COVID-19 pandemic period than pre-COVID-19 pandemic period (RR = 1.36, 95%CI: 1.26–1.56, P < 0.001). The number of deaths was significantly higher within 24 h of hospitalisation, although the mortality rate for more than 24 h after hospitalisation during the COVID-19 pandemic was unchanged as compared to the pre-COVID-19 pandemic period (no fatalities within 24 h: RR = 0.97, 95%CI: 0.90–1.03, P = 0.287), (fatalities within 24 h: RR = 2.80, 95%CI: 2.44–3.22, P < 0.001). Although no unit root was found for all the variables used in the ITS, a harmonic adjustment term was inserted in the ITS model because of seasonal variation. No autocorrelation or partial autocorrelation was observed in the adjusted model.